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Should I replace ac compressor myself?

gladesrunner on Thu April 02, 2009 10:17 PM User is offlineView users profile

Year: 1995
Make: Ford
Model: F-150
Engine Size: 4.9 ltr
Country of Origin: United States

Hi, My compressor just stops when driving. Be blowing ice cold then warm. Intermittently. Took it to local mechanic. $800.00 estimate to replace compressor and dryer or just the necessary parts to replace. I believe it does need replaced and though I have been doing my own automotive repairs for years and have or can get all necessary tools I wonder if I should do this myself. A/C work and automatic transmission tear downs are two areas I have little experience in. Basically to de-pressurize the system and then recharge it is where I am weak. I can usually go by the manual for any mechanical removal and installing of the parts themselves. Plus I enjoy learning more. I like to save money and I actually trust my work. Thanks for any suggestions. Sincerely John in S. Fl

1995 F-150 XL 4.9 inline 6, 157k

Chick on Thu April 02, 2009 10:29 PM User is offlineView users profile

Before you start taking your system apart, there are two things to check. One is the cycling switch. Could be faulty after years of use. When it stops blowing cold, jump the two wire switch on the accumulator. If it starts blowing cold again, change the switch. About $19.00 If that doesn't start the compressor, try tapping the outer clutch hub, if it starts, you might just need a clutch gap adjustment, also common of those compressors.. Check the gap with a business card, should fit snug between the hub and the pulley .02.. let us know what you find. If it blows cold and there isn't any noise, you might not need a compressor.. Hope this helps..

PS: Jumping the cycling switch, I mean the "wire harness" not the switch itself, when unpluged it does nothing, jump the two wires that go to it.. Also, do not drive with the switch jumped, it's just to test the switch. Driving with the switch jumped can cause evap freeze up..

Email: Chick


Freedoms just another word for nothing left to lose

Edited: Thu April 02, 2009 at 10:33 PM by Chick

gladesrunner on Thu April 02, 2009 11:05 PM User is offlineView users profile

Thanks, the mechanic I went to took a screwdriver and did some sort of quick prying action, engine running, and the outer clutch on the compressor, where he pried, started spinning. He said "dont try this at home". Then stated "its your compressor." I will listen for noise. I will do the tests you described and let you know what I find. I may not need to replace. Great running truck, even if she is a gas guzzler. I am glad I joined the forum. Will donate.

1995 F-150 XL 4.9 inline 6, 157k

robs on Thu April 02, 2009 11:41 PM User is offlineView users profile

i would first take Chicks advice before paying a mechanic that amount for a simple repair. On the other hand, if the compressor is the case and you will need to replace it, i would highly recommend staying away from any remanufactured FS10 compressors and at the same time, investing money into buying the tools and parts and doing it yourself. I added all the parts that you would need and you will be looking under $375.00 for the compressor, condenser, drier and orifice tube which are listed HERE. If you get any of the DO IT YOURSELF KITS you will still be under what the mechanic quoted you, plus you will have all the tools and knowledge for the next time and like you said, you want to learn about this and trust your work, so hand in hand, that would be the best option i think.

chris142 on Fri April 03, 2009 12:21 AM User is offline

Try this. With the engine off and the key in your pocket remove the bolt in the center of the AC clutch hub. You will need a 8mm or 5/16 socket. An air ratchet is best to use for this.

Once the bolt is out you can easily slide the clutch hub off. There will be a small shim either stuck inside the hub or still stuck to the shaft thats sticking out of the compressor. Remove the shim and put the hub back on.

See if that helps.

NickD on Fri April 03, 2009 6:23 AM User is offline

Ha, reminds me of my wife's most trusted mechanic in Venezuela, with her 97 Corolla, PS belt would squeak on with the steering wheel at the stop. Opened the hood, belts were in excellent shape, three of them, the PS with it's own belt was loose, needed just a 14 mm wrench to adjust it. Down there, wanted a hundred bucks for a cheap Taiwan set, do you know of anyone we can borrow a wrench from? Her most trusted mechanic, we drove over, she translated for me, would not loan me the wrench, was way up on top, wouldn'g even have gotten my fingers dirty. He said, the only way he would do it, is to replace all three belts, could not argue with him, but wanted 1.5 million Bs to do the job. That's $714.00 US, just because one belt was a tad loose.

Should mention in Venezuela, can expect to pay anywhere from 10-20 times as much for any automotive parts, but gas was only 9 cents a gallon. My solution was not to turn the steering wheel against the stops, and will try to smuggle in a 14 mm wrench the next time we go down there.

One darn good reason to change a compressor is because it's seized, another is that it has an unrepairable leaks, one like hell of a corroded mess, but sounds like you have clutch engagement problems. Like it was mentioned, the clutch uses shims, and does wear, especially if you run your AC in cooler conditions where it cycles on and off more frequently, good to avoid that by the way. I prefer to use a feeler gauge, and like a gap of 20 mils, but can go up to 30 mils, much more than that, and it won't pop in. So before even removing the hub, would check the gap first to find out where it is.

Also like to do a clutch current test, use a power supply for that, should pull in solid at 10 Volts, and current is between 3-4 amperes, but the most important thing, is that when the power supply is left on, and the clutch coil is cooking, the current DECREASES as the copper heats up. Can have a case where current increases as the insulation on the wire is worn, coil expands with heat and get shorted turns explaining why it doesn't work when it gets hot. Can use your battery and an ammeter to do this test. Meters with a 10 ampere range can be purchased now for ten bucks. Remove the coil connector first, and do not apply voltage to the vehicle connector, only directly to the two coil terminals.

Yet another works when cold but not when hot are the switch contacts activating the compressor, need your circuit for this, some use the cycling switch directly, others use a relay with dirty contacts, these will drop a voltage of greater than 0.1 volts, if this is the problem, changing the compressor with even a brand new on, will not fix the problem. Even found problems in the mode switch on the climate control panel, Ford uses bare copper with a grease that turns rock hard and the copper turns green, copper oxide is an excellent insulation, not really ideal on a switch, but use just a voltmeter to measure voltage drops, across these devices, should be well on 0.1 volts under full load, also found high voltage drops across fuse holders, and the ignition switch, again, all unplated copper.

Find out what the problem is. Mode switch went out in my daughters 98 ZX2, checked with Ford first, was only nine bucks, so not worth fooling with, even for a frugal guy like me, but was a combination vacuum and an electrical switch and that rubber looked rotten. That took me about ten minutes to find, with 14.5 volts at the battery terminal, was only getting 11.5 volts at the turn on clutch coil, was losing 3 volts in that rather simple circuit.

mk378 on Fri April 03, 2009 11:06 AM User is offline

Sure sounds like the gap is too wide. Do what Chris and Chick suggested about taking the shims out and that should take care of it.

I'm not going to say you have a bad mechanic because he'd rather replace the whole compressor as a unit. Some don't want to "tinker" with a part because if it doesn't hold up, the customer will come back angry, expecting him to replace whole compressor now at the shop's expense.

TRB on Fri April 03, 2009 11:14 AM User is offlineView users profile

Could use a feeler gauge to check that the gap is plus or minus 20 thousandths.


When considering your next auto A/C purchase, please consider the site that supports you:

NickD on Fri April 03, 2009 11:27 AM User is offline

Some don't want to "tinker" with a part because if it doesn't hold up

True from the mechanic's point of view, but is a 14 year old vehicle with probably a lot of miles on it. Still feel an electrical check is in order as a volt or two low will cause clutch slippage exacerbating the wear. When I stop at a rest station, do a walk around with the back of my hand toward the tires and the brakes to check for excessive heat, also added the AC clutch to that routine, can tell if it's running hot, just takes a second.

In the case of my wife's mechanic, told her to tell him I would sign a disclosure freeing him of any liability just to tighten that belt, 714 bucks is a lot of money and her car is getting old. Still no go.

Ford and GM truck are notorious for poor electric contacts, and as I said, a new compressor would not fix that, you have to learn the cause of the problem.

gladesrunner on Fri April 03, 2009 10:29 PM User is offlineView users profile

Thanks for sharing your experience all of you. Im anxious to perform these checks though I wont be able to for a few days. Going to Sarasota this weekend. The gap will be my first check. I will try the suggestions and find the problem. Dont worry it wont be long for me to get to it, the humidity is setting in down here. But boy, we had a great winter. Bowers garage is where I went and he was reasonable when his ac guy got my 1983 280zx blowing cold. I understand he has to make a living also, but he also charged me 80 to add freon 3 months ago. My truck has 157,000 on it, so if the problem persists I like Robs idea of the do it yourself kit. Tools and my truck are my bread and butter. I would like to be able to gain a working knowledge of auto ac if only for my own vehicle. Im an electrician in West Palm Beach and work is slow in my trade. Check gap, switch, check shim, elec. checks, this is a blessed site. Will let you know how it spins out. Thanks.

1995 F-150 XL 4.9 inline 6, 157k

Dougflas on Fri April 03, 2009 11:54 PM User is offline

If you purchase the DYI kit, spend a few more $$$ and buy the onee with the 2 stage pump. It'll provide a much better vacuum.

gladesrunner on Mon April 13, 2009 10:29 PM User is offlineView users profile

Two days ago I removed the clutch hub and found 3 very thin shims. I removed them and now the gap is around .030. Since I did this my ac has been working fine. I have not been using the ac as much though these few days because it has been nice out, but so far so good. I will be amazed if this is all that is required. Thanks

1995 F-150 XL 4.9 inline 6, 157k

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