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An air compressor bogging down when running is a very common issue for users. This article will present to you the possible reasons why this is happening, reader questions and responses, and an opportunity for you to post about your problem and receive some help!
Table of Contents
- Why is an Air Compressor Bogging Down?
- Most Common Reasons for Air Compressor Bogging Down
- Most Frequent Cause of an Air Compressor Bogging Down & How to Test
- Youtube Demonstration
- FAQs (Frequently Asked Questions)
- Reader Questions and Responses
Why is an Air Compressor Bogging Down?
By that, I mean that the air compressor starts normally, it begins to build pressure in the tank, but at a certain point, the compressor motor begins to slow down.
The compressor motor begins to labor, the compressor motor slows, the sound changes, and the buildup of air pressure in the tank either stops completely or slows substantially.
Sometimes, when an air compressor bogs down, that process causes a problem with the power. The motor may pull too many amps, and the circuit breaker lets go. Or, the on-compressor thermal reset button will shut down the compressor due to motor overheating.
Most Common Reasons for Air Compressor Bogging Down
Diagnosis of the problem may not be that easy. There may be many things that can be the cause of the bogging down. Here are some of the most common reasons why an air compressor bogs down include:
- Use of a too-small extension cord to power the compressor. If an extension cord is being used, remove it, and plug the air compressor power cord directly into the wall socket to see if that helps.
- Use of a power bar to power the compressor. Same advice. Remove the power bar from the power supply and see if that helps.
- Too many other power-drawing appliances on the same circuit as the feed to the compressor. Ideally, an air compressor should be powered from a socket that leads directly back to a 15 amp (minimum) or a 20 amp breaker or fuse at the panel. If other appliances are in the line that feeds the compressor, shut them all down, and test the compressor again.
- The compressor unloader valve has failed. To test this, open the tank drain and let all of the air out of the tank. This will emulate the unloader valve function, and at the same time, remove water buildup in the tank. Close the drain and power up the compressor to test. If the compressor starts easily and runs up to cut out pressure, it’s time to service or replace the unloader valve.
The previous checks are simple. There is one more that you should do before getting to the more complex checks noted below.
If the compressor is belt-driven, remove the belt (power cord out please) and turn the pump sheave by hand. If it turns relatively easily with no binding, that helps eliminate the pump as the cause.
Most Frequent Cause of an Air Compressor Bogging Down & How to Test
The reality is that the most frequent cause of an air compressor bogging down on start-up is a failing start capacitor. It’s now time to test this component, visit our How To Test A Start Capacitor On Air Compressor Motor guide!
If the start capacitor checks out, and your compressor has a run capacitor, check that one next. If either is not up to snuff, they must be replaced.
Now it’s decision time. Do you take your compressor motor to an electric motor shop for a load check, or do you tear down the pump to see what’s what? Your rotating of the pump sheave may help.
If there was any hint that the pump may be malfunctioning mechanically, tear down the pump to check the piston rings, intake and pressure valves, and general condition of the pump innards.
If you feel that the compressor pump is okay, and the power supply to the motor and the motor caps are good, it may be time to pay for a motor load test.
If you opt for tearing down the compressor pump, depending on the age of the compressor and level of use (ie; did you forget to put oil in a lubed compressor?) you may want to replace the piston ring, valve plate, and ALL gaskets to ensure that when you reassemble the pump, none of these items can be an issue for some time.
Make sure when you install the valve plate that it is right side up, else your compressor pump will not work.
One last thing, you should know the duty cycle of your air compressor and make sure you run the compressor within this time frame. Overuse of the compressor can be a factor in why an air compressor is bogging down.
I have picked out a useful youtube demonstration that may help you with your bogged-down compressor!
FAQs (Frequently Asked Questions)
It is likely that any of the following reasons could be the cause of your air compressor bogging down: extension cord use, too many power-drawing tools, failed unloader valve, or a failed capacitor.
Weakening of the insulation around individual wires in the motor coils tends to be the beginning of electrical failures in the motor that cause bogging down. Thermal stress, contamination, and movement of the winding due to magnetic forces in motor start-up and shut-down are the main causes of this weakening.
Reader Questions and Responses
The compressor bogs down at 20lb pressure and will not kick out?
When I turn the compressor on it builds to 20lbs and then the motor bogs down and won’t kick out. There is a new pressure switch on it. The compressor sat for years without running so I drained the oil and refilled it. It still does the same thing. Any ideas.
Are you saying that it worked fine after the many years of sitting, or are you saying that the first time you used it since it sat, it bogs down at 20 PSI?
Make sure your compressor is getting clean power, no extension cords, and check the intake filter to make sure it is clean as well.
More info, please. What make of compressor, what model number, and what voltage?
The Compressor Kicks On but Sounds like the Motor Is Bogged Down
2hp motor air compressor. Initially builds pressure to 115 psi. After it turns off it sits and does not look or lose pressure.
When the compressor does kick on, it sounds like the motor is bogged down and never builds pressure back. Stays around 20-30 psi and won’t build past this amount UNLESS I unplug the power cord and plug it back in.
I can’t find any leaks and upon checking the reed/ flappers.
I now smell burnt oil, the top of the valve smokes from burning oil, and it’s very hot. So hot it melted the plastic threads on the filter housing!
So, I imagine I didn’t install the roads correctly. do I need a new reed/ flap set? Why will the compressor build 1115 psi and then not unless power is disconnected?
I can’t afford a new, used one and really need this air compressor to finish siding my home for homeowners. Any help is most gratefully appreciated.
Michael, you don’t indicate what make or size the compressor is, or what the power supply is. Tell me about the extension cord you are using. That may be an issue.
That your motor is overheating suggests that you’ve got…
a) a power supply problem
b) a motor problem
c) a start/run capacitor problem
d) an unloader valve that isn’t working properly
e) a valve/gasket problem
Air Compressor Bogs Down
I have a 60gal 3hp air compressor. Worked great until last week.
I decided to fix it up after many years of faithful service.
The 5hp motor was having a hard time so I got a new 3hp (No 5hps are available and since it was a 3hp head WhatTheHell) it worked great one time but the pressure switch was going out.
I replaced the bent and dented old copper tubes with new ones.
I replaced the switch but now the motor bogs down upon reaching 50lbs and the motor STRAINS and pops the breaker. the head gets really hard to turn until it bleeds off thru the valve by the pressure switch then it’s ok until it gets hard to run and the motor bogs again. NOTHING was actually changed in regard to the head. Just the switch, motor, and tubes. Why is it bogging down? I’m afraid I’ll fry the new motor at this rate. Why is the head acting up?? what can I do about it?
JC, this part of your post confuses me: “I have a 60gal 3hp air compressor” and “The 5hp motor was having a hard time so I got a new 3hp”
I surmise that you are powering it with 240 VAC as a 5HP sure wouldn’t run on 110 AC power.
If the original motor was a 5 HP, putting a 3HP on that pump would likely cause the problem. The motor bogs down because it cannot overcome the load being developed by the pump.
If the original motor was a 3 HP, and someone put a 5 HP on it, perhaps they changed the sheaves then, and the wrong size sheave could contribute to the problem.
Remove, clean and replace the tank check valve and see if that helps.
If you have any questions regarding an air compressor bogging down, please leave a comment below, with a photo if applicable, so that someone can help you!
Recently purch’d a used, but seldom-used Central Pneumatic 2.5HP model 61454. my issue is compressor will occasionally, hot or cold, bog down when starting @ the 90psi cut in pressure, tripping the thermal overload before ever tripping the 15amp circuit breaker. My garage has no power, so my elec power suppIy is furnished by running a 50 ft 10amp extn cord plugged into an outside light on my mobile home, which is on a 15amp circuit breaker-i make sure nothing is running on that circuit in the mobile home, including the outside light bulbs before i head to the garage.… Read more »
Yeah, that’s the cold start valve. What you did masks the real problem.
Your problem is the check valve at the tank, probably. Does the tank ever leak down a bit after the pump stops? That’s a leak in the check valve, which will escape at the pressure switch. You might try cleaning it before you replace it; they get gummed up sometimes.
Also, unless “running a 50 ft 10amp extn cord” means 10AWG, you need at least 12AWG as that needs 14+amps. If your check valve is OK, then this would be the problem.
I have an Ingersal Rand that I purchased from Tractor Supply cheap, (like new) with a burnt up motor. 60 gallon tank, I replaced the motor with a WEG motor 5hp, 3500 rpm. All seemed good until I found the breaker tripped and found starter capacitor burned up. Replaced it a seemed fine until two weeks later another blown capacitor. I’m assuming the motor is struggling to come up to speed and burning capacitor up. It only happens under a load. Any suggestions??
“I’m assuming the motor is struggling to come up to speed and burning capacitor up.”
You’d probably hear it struggling if that were the case.
Have you checked the run capacitor?
Have you checked the centrifugal switch? The capacitor is supposed to be disconnected after the motor starts, so if it’s really that that is blowing, it points to the switch contacts possibly welded.
I have a 60 gal Campbell Hausfeld compressor.
3.2 RHP wired 240v
Starts no problem gets up to 60 psi or so and then starts to labour. Speeds up slows down until up to pressure (135) unloaded works when it shuts off.
Runs great when pressure in the tank is released.
Doesn’t trip a breaker when it slows.
Could it be the pressure switch.
Put in new gaskets and has oil is full in the pump.
Odds are it has a run capacitor. I’d check that first.
If that’s not it, please provide an actual model or at least a picture showing the pump and motor.
In my case my 60 gallon, 3.7 “running HP” (whatever that means) Kobalt compressor would run to about 40 psi then stop and hum. I suspected a bad run capacitor and checked both caps and voltage at the motor (242v). After removing the belt guard I noticed a huge amount of slack in the belt. All I needed was a belt tightening and it’s running like new.
I have a 2005, 60 gal., single stage, 7ph (peak), belt drive, Sanborn air compressor which is wired directly to the breaker box by a short piece of romex wire. It has performed well for 16 years until recently, receiving regular but modest use. All parts are original. Model LA7006056. In recent months it performed fine at start up but then the motor slows down and has a lower, labored sound when the pressure is roughly 60psi, although the compressor did still go to its usual maximum (120psi or so) but perhaps more slowly than when the compressor was newer. Then last Saturday,… Read more »
Any resolution to this? Sounds exactly like my 18 yr old Sanborn 60 gal single stage. Labors for a bit around 60-90 and build pressure slowly but eventually still makes it to 150 psi. Same 8g power source it has always had. Used it pretty heavily last summer and the paint is melted on the compressor head but expect I have more going on.
Hi Steve! No resolution. Six months ago, it sounded so labored at roughly 60psi that I turned it off and tried to find the problem. Over the weeks back then, I replaced both capacitors, etc. When I could not find the problem and was in a real “pinch”, I used the compressor. To my surprise, I found it started sounding better at roughly 90psi and that it then worked OK. I still don’t know what is wrong with the compressor but I am now using it again, despite it sounding very labored in that mid range. It also seems to… Read more »
If you don’t have weirdly bad bearings, I’d be thinking valve plate/valves.
If they leak a certain way, air moves between the cylinders instead of to the tank.
Thank you, Doug! I appreciate the in-put! If the valves/valve plates were bad, I would think that when the tank was full and the compressor shut off, I would hear air leaking because the valves did not seal. Is that correct? I tried this and everything is quiet, that is, no sound of air escaping. Your thoughts please?
That’s good. It means the check valve in the line from the pump into the tank is sealing, holding the air in the tank. If it were leaking, you’d have air coming out of the unloader valve in the pressure switch.
Whatever is wrong, it’s in the pump, unfortunately.
Thanks! Yes, it is a puzzle what is wrong. The belt and belt pulleys appear lined-up and are not frozen.
I have a Campbell hasfield 230 v 2 stage compressor this unit is brand new. The motor bogs down after building 30 psi. I have it on it’s own 30 amp 2 poll breaker. I can see the switch on the motor open and close which I can assume it’s going from start to run capacitor then it will throw the breaker. The cord is # wire and only 2ft long. Motor model # 56S34D5M
#8 wire sorry
I know this is a stretch, but have you verified that the motor is actually getting 230V?
If it is, then it sounds like the second stage has bad valves, notwithstanding it being new. Assuming it has oil, of course. What model is it?
Xc802100aj (agm46) Campbell Hausfeld the pump is xc002500av
AC power at the switch 230-240V?
Did you do the break-in?
Suggest you check the capacitors and connections – might be loose.
The oil is good the capacitors are good I had them checked there hasn’t been no in a time for me to break it in. I bought it from an auction I’m assuming there was something else wrong with it when I bought it. I ordered new valves hopefully that might help.
May as well verify the bearings while you have the heads off.
Bill, I have a speedaire 120V 2HP compressor. (1NNF4) Anyway it bogs down pretty quickly. When I got it it would not start at all so I replaced the starter capacitor. It would then start, but bog down so I thought maybe the run capacitor and I replace that too. It runs a little longer but then bogs at maybe 10 lbs or less and never really builds much pressure. It will stop turning. The pumps rotates freely and will move by hand even when bogging down. The motor runs great without a belt. I pulled the check valve and… Read more »
That’s a vertical twin Campbell-Hausfeld pump. The only way I can account for these symptoms is a blown head gasket, between the two cylinders. Air is like water in that it will take the path of least resistance. So when one cylinder is compressing, most of what should be going to the tank will instead flow to the other cylinder, is is creating a vacuum to get more air to compress, But when it goes to compress, the other side is making a vacuum and so the air goes there. Pretty soon, there is too much air to compress, and… Read more »
Have an old (1995) Campbell Hausfeld 2 stage compressor. Motor runs great, had it rewound couple years ago. With the belt removed the compressor turns by hand well. Trouble is it builds to about 80psi and then slows and screams, belt slips, motor continues to run but belt slips and I unplug.
Probably bad valve on the HP intake.
I recently acquired a new to me vintage Kellogg American B321 compressor. I replaced the belt, the wiring to the motor, and put on a new pressure switch. Plugged her in and she started first try! Amazing. I have not gone into the guts of the compressor yet, change the oil, etc. because I wanted to see what I was working with first. She runs great until around 45 psi — then it bogs down. At around 50 psi I turned it off as it was sounding rough. I drained the air, did the same test and realized it was… Read more »
1) Don’t think I’ve seen a manual, but there’s a chance you can find one for sale, if you look around…
2) Maybe. Did anything slip or scream?
3) Yes. I’m guessing this is a two stage pump (why no pix?). If so, this symptom is usually the second stage intake valve(s) stuck or broken.
Hi, looking for some help and advice on my compair holman lt10 cummins compressor. it is running on full load for approx 10 ins and then cuts out completely.If anyone can help i would be grateful.
Has it been working OK for you til recently?
How, exactly, does it cut cut out? Is it at full pressure immediately before that? Then does it hold whatever pressure, or blow down? Done any maintenance on it lately?
Mid 90’s Chicago pneumatic diesel 185 cfm rotary screw compressor bogging down after ~20 secs of run time. You can start it again immediately and it bogs down quicker. It doesn’t have any fluid level or heat sensors other than the gauges for safety cut off. Oil separator element isn’t clogged. Would this be an unloading valve issue?
Maybe. What’s the pressure at bog-down? Got a model? Maybe some pix?
About the time it makes 100psi it starts to sound labored and dies. Comes to a more abrupt stop than switching it off. The problem originally started after about 10 minutes of run time and now does it at every start up.Thanks
So it’s blowing down when it stops – that’s good.
Yeah, as you suggested, it should be throttling down and closing the inlet (loading) valve at 100psi, given it’s rated at 102. That’s what it been running at, right?
What if you crack open a service valve around then? Does it regulate to 102 or?
Is the throttle working, or maybe stuck?
Can you get into it to see the inlet?
I don’t have a CP manual, I’ll see if I can find one.
Do you have one for it?
I have a craftsman 191.158210 when I start it it runs fine and then bogs down about a minute. I let the air out that has built up and run it again, it still bogs down. What can I do
…I guess you mean a 919.158210 ?
Have you checked the belt tension?
What bogs down? The motor or the pump? What’s the pressure when it happens?
Craftsman 2 HP 230V 106.154780 compressor. Starts and runs but bogs down as soon as some pressure builds, then motor reset button sparks on and off. I disconnected everything but motor and compressor. Runs fine with no load, just blowing air from tank and small compressor head fitting. If I put my fingers over outlet from tank and small fitting in the head, pressure will build for 15 seconds then bogs down, I see a spark at the reset button, tries to speed up again, but immediately bogs down. It will just keep doing this but won’t build more pressure.… Read more »
Hi Did you ever fix this issue? I happen to have to same compressor and have the same issue. I just bought a new pressure switch, replaced it and it has the same issue. It is very frustrating.
Doug – no telling, and I don’t know how I missed Don’s post.
But this sounds like a run capacitor issue, most likely.
It or they will be under the bump on the motor. Remove the bump (cover) and check the capacitor(s). One or both, if there are two, will be bad or a wire to it will be broken, if you’re lucky.
OK, CAPACITOR HAS BEEN PURCHASED…i’LL LET YOU KNOW HOW IT Works out. Thank you for your time and reply.
I have a speedway 60 gallon 3 hp oil filled. When it get to around 100 psi it starts making noise like it’s freezing up. It’s hardwired 20 amp 10 gauge wire. The pump turns easy by hand and you can hear it compress air. I don’t know if it’s the motor or the pump
If it’s a two-stage, that often means the second stage has bad valves…what’s the normal cut-out?
My 60 gal compressor starts fine, may run a little slow, but as it reaches 70 or 80 psi it labors real bad, and squeals very loud as it acts like its seizing up, after approximately 30 seconds or so it manages to push through it and continues to fill. As I use it the pressure drops normally and when the pump kicks back on the same thing happens. Surely these exact symptoms are a true indicator of what is wrong, can you diagnose this acurately based on my info ?
No. Can you give make and model number of your machine?
Failing that, pix of the thing ?
Have same deal.Check valve cleaned. Ingersol Rand . 60 gallon 5 hp. Unloader seems good
Please see my reply to Bruce.
I have the very same problem Bruce
i have the same problem . I have a husky 60 gal compressor when it act up it smiles like the belt is burning . but the belt not slipping.