A/C Compressor Not Coming On

[deanamal]

Hello. When it rains it pours. Just yesterday I posted about power window issues and today my A/C went out. Here are the following symptoms and things that I did to check.

1. When cycling the a/c switch on and off, I hear no difference from the engine when running as to the a/c clutch engaging/disengaging.
2. It blows ambient air with the a/c on max and temp control full cold and when moved to full hot, it definitely blows HOT air. By the way, I live in DFW Texas and it's been murder over here this summer.
3. At the back of the compressor is a round plug. With the engine on and a/c on, the terminals on the compressor ohmed out to zero. I jumpered the terminals in the round plug itself and no clutch engagement - if what I was hoping for here is correct at all.
4. I plugged the round plug (pressure switch I'm guessing here) back in and it makes no difference.
5. I swapped relays in the power distribution box in the engine bay with the PCM relay and that made no difference - this was swapped with the WOT A/C relay (wide open throttle relay).
6. With the engine off, I pulled the flat oblong switch at the front of the compressor nearest the clutch and looked at it. It is a two terminal plug with a black and a black/yellow wires leading to it. The plug has considerable (extreme) wear on one side to the point the orange washer that goes around the plug to act as a seal is totally worn off on one side and that same side shows wear to the point that both terminals are exposed through the plastic plug housing.
7. With the engine off, I tried to jumper a wire from the terminal that I pulled the plug from the clutch to the + terminal and did not hear the clutch try to grab. To get to this terminal, the compressor/clutch is low in the engine and the lug goes in blindly so I used a mirror to make contact with either of the two terminals by the clutch - I got nothing and I did this on advice from a friend. I was told this is where the clutch gets its power from the relay?


I have seen on other threads that it may be a low pressure problem and I guessing the best thing to do is someone test the pressure with a set of gauges before I start shelling money out for freon and stuff. I have seen at parts stores DITY freon kits with gauges supplied. Are these worth the extra money?

Any suggestions here would be greatly appreciated. Thank you for your time and consideration!

 

[Lube]

Yup, you've got no refrigerant. Here's the issue, if you have a refrig. leak, you also have an oil leak - so you'll need to add a bit of oil also. You can just put more gas in it, but that won't fix the problem, which is that you have a leak that must be found and fixed, too. The most common leak points are:
compressor shaft seal, compressor casing seal - or any other mechanical joint in the system.
The one thing you can do to make sure it's not just a dead clutch (they do go bad) is to get a couple of jumper wires and go straight from the battery to the clutch - if it engages, it's not the problem. Don't do this with the engine running. Too much chance of your jumpers ending up in a pulley.

 

[deanamal]

@Lube - Thanks

Thanks for the reply. I was hoping for low refrigerant problem but I'm wary to be careful what I wish for. My worst fear was a bad compressor or clutch. It's near impossible for me to get to a position to jumper the contacts at the clutch. This compressor is low on the front and if you were to look at this compressor standing at the front of the vehicle, the plug goes in about at a 5 o'clock position. If I had a spare plug where I could cut and jumper these wires and touch these to the battery posts, then yes, it might work.

I have seen refrigerant kits at the auto store that has gauges with it and a can of dyed lubricant to trace for leaks. My question is; When adding the lube/refrigerant, does the compressor need to be turning or will the freon be drawn into the low pressure side and then ultimately kick the compressor back on?

Many thanks again for your help!

ps. My Ford is a 97 Explorer XLT 4.0L SOHC
I just bought this a month ago and I love it and the way it rides. For the month that I have owned it, the engine bay is extremely clean and most parts look brand new. I have noticed an oily film being deposited on the radiator shroud and over the front of the engine bay by the headlight covers. I'm guessing this a freon leak coming from the plumbing somewhere?

 

[joecrna]

If the system is undercharged the compressor will not engage or will cycle frequently. A cheap place to start is to buy the large can of R134A at the parts store. One kit will come with a gauge and tube to hook up to the low pressure side. Usually about $5-$10 more than just the can of the same size. Follow the can directions carefully. You really need a little help to do this properly, someone inside the car. The can is pressurized and will start to fill the system whether the compressor engages or not. Does it even cycle at all, maybe only engages for a second or so?

Start by hooking up the gauge and can with the engine off but don't push the button to open the can. You will get a horribly unreliable reading that should be less than 40 psi. If so, unhook the can and procede with the instructions on the can. If not, unhook and continue with the instructions on the can but write down all of your pressure readings as you may need further help with this later. It may take 20-30 minutes to completly empty the can if that is necessary. When the gauge that came with the can reads in the good zone or about 35-45 psi for our system, you are fully chargered and all should be good. Remember, overcharged is worse than undercharged.

 

[deanamal]

@ Joecrna

Everything was fine for the month I had it. To be quite honest, I really paid no attention to the operation of the a/c compressor as most of the time, I have my young daughter in the car and she always has the music blaring. I didn't notice anytime that the air output would warm up or cycle colder. My wife returned from the store saying the a/c isn't working. That was my first sign! When I have the engine running and turn the a/c on, I don't hear a click and I can see that the front hub of the clutch is not spinning at all. Throughout the month I owned it, I had changed the oil and worked in the engine bay a few times to change out signal lamps and such and always noticed a greasy film at the front where the headlight access flaps are, in front of the radiator shroud. I would wipe this off and another week would go by before I popped the hood and there was that greasy film again. This has me thinking that there's definitely a freon leak in that vicinity.

I really appreciate your reply and some pointers on this refill. The only other time I had done this was when I was in my early twenties and attempted it on an old 72 Nova I once owned. Back then it used the old stuff and I had heard of times when the novice user would tie the can onto the high side and blow themselves up!

On this Explorer, I have noticed a freon nipple on the passenger side of the engine bay where the plumbing enters the blower/evaporator? I have yet to buy this kit but I'm assuming this is where I deliver the freon to?

Also, on the right side (driver) of the engine bay, there are two nipples up front near the radiator. One nipple is on hard tubing of smaller diameter to which I'm assuming this is the high pressure side since it seems like it is coming from the compressor. Right next to that is a nipple on a flexible tube that runs down below the radiator and ties in on the extreme right/front/low side of the engine bay. What is that for?

Again, I want to thank you for your help and it's much appreciated, I can assure you!

 

[joecrna]

First, you must be as old as I am. Your '97 Ford uses R134A instead of the old R12. The valves are now size coded to prevent incorrect hookups. The low side you want is indead on the passenger side on a larger diameter tube. The freon flow is coming from the evaporator and is now low pressure at this valve. It then goes to the compressor and is, well compressed. At this point it is high pressure, hot and in a smaller tube headed to the condenser (radiator like) where it looses heat and condenses into a slightly cooler (still hot) partial liqued. That oil you mentioned is probably from your AC leak as you said. If it came back in a couple weeks it is unlikely a simple recharge will offer a very long fix (maybe temporary). As for those other valves, i would need to look under the hood of my Explorer. Unfortunatly, I am at work now and drove another car.

You really need help to fix or trouble shoot this. It's impossible to hear the clutch kick on reliably and you need to be able to watch it as it may only run one second and than back off. If its completly empty, it won't cycle at all.

Here's what I did a few months ago. Got everything ready, asked the wife to come out and give me a hand for a minute or two and had her get in the car with the hood up and windows down. I had her turn off all the accessories; AC, radio, fan all off. Asked her to then start the car and keep the idle elevated(1200-1400rpm is good, it assures the compressor can turn fast enough to do its job). I pretended to check something at this point, then said turn the fan on high and set it to vent. I pretended to check some more and asked "Is air coming out hard now" "yes" she said. Now turn it to AC max. "OK". "Is the fan on high, AC on and set to coldest setting?" I asked. "Yes", she said again. "Still blowing warm air" I asked. "Yes" "OK I told her, we may be able to fix this. I hope at least. The last time the AC fix cost $1000. I need to go to the store to get some stuff" I told her.

An hour later I was back from the auto parts store with my large can of freon/oil with the little tube and gauge ($25 here in CA, plus $10 deposit). The explorer still sat in the garage just as before. I went inside and asked her if she could help me again. I put on my long sleeve shirt and leather gloves and asked her to turn everything back off and start the truck. I asked her if everything was still the same. She said, "It still blows hot". I said, "Good". I shook the can and hooked up everything just as the directions on the can said. I spent that hour at the store reading the can a few times so I knew what to do. I than presented her with a thermometer and asked her to check the temperature of the center vent and went back out under the hood. She yelled out, "98 degrees". " Wow, thats hotter than it is outside", I said as I opened up the can push valve and began to fill the AC low side while rocking the can back and forth just as the can said. Every few minutes I would say "Is the Idle still 1200-1400rpm, is it any cooler yet?" She would say "yes and it maybe a little cooler" As the pressure came up to 25psi I asked her to check the temperature again. "Its 75" she excitedly yelled back. I then stopped filling and walked around to her window and said "My hands starting to hurt". All that rocking the can back and forth for the last 10 minutes you know. "So its starting to cool" I asked. "Yeh" "OK, keep the idle speed where you have been, and keep the thermometer in the middle vent. We need to add a lot more freon".

This continued on until the freon gauge read 45psi (about 25 minutes in all), a little on the high side of the good zone on my cheap little can gauge. I yelled out "What's the temperature now?" She said "58 degrees". I then asked her to shut everything off and then turn the engine off as I disconnected the filler tube from the low side and was careful to screw the cap back on the valve (there is an O ring in there to help prevent leaks as these valves often leak a little). I walked around to her window again as I cleaned my hands and we discussed what a remarkable job the AC was now doing. I asked her to restart the engine and then turn the AC (set to high) off and on a couple times as I watched the compressor clutch engage and release each time (never cycling before she shut it off).

I then said to shut everything down, turn off the Explorer and lock it up. As she came around to the front, I closed the hood. I than explained how I could never have fixed it without her and we would have had to take it to the shop (remember that $1000). I told her how its impossible to get it to work without 2 people working on it. The next day she drove it to work and told all her friends howshe had helped fix the AC on the Explorer.

At least thats how I remember it. Seriously, to do this right, you do need a little help. Then its no big deal. That leak, if it truely is AC oil, will be a little bit harder to fix. But not much, and now you have an assisstant to help you save the family $1000.

 

[Lube]

If it's oil from the compressor, you're kinda in a bad place. Usually, the leak from the compressor will be from the shaft seal, which is behind the clutch. Most parts stores don't even carry it as a repair part (NAPA does), but unless you've got experience working with mechanical seals I wouldn't recommend trying to do it yourself. Your only option then is a new or reman compressor.

 

[deanamal]

@ Joecrna and Lube

Hey guys! I truly appreciate your help in all this. Joe, your story is awesome! My wife calls me "Superman" for all the stuff I've had to do since getting the truck (replace hood struts, change the oil, fix the power windows, replace the cruise switches), pretty much easy stuff.
When I was in high school, my dad helped me get that 72 Nova, only 4 years old then and I loved it. I would help him replace brakes, tweak carbs, replace water pumps/alternators and such. I always considered myself handy.
Back to the wife...so, when she calls me that, I just go with the flow. I'll definitely get her involved in this project and who knows what that might get me?!? A/C problems were always a head scratcher for me. It was either low freon or bad clutch. All this computer controlled stuff keeps me in circles. I'm guessing on shelling out a few bucks on some freon with dye in it and see where it leads me. I also have a friend that has a small auto shop but he's always in the pit whenever I call and I feel bad to bother him but he said he'll come out in a few days and take a look at it and put some gauges on it. So, hopefully it's a leak at a connector but am prepared for the worse. Again, I really appreciate the time you've taken to share that story with me as well your experience. Many Thanks!

@Lube - Thanks for the advice there. The compressor looks clean around the clutch, pretty much all over really. I don't feel any oily residue on or near the compressor. I have a sinking feeling it's coming from the condensor area. I haven't really looked at it closely in this area and don't know if there are any quick disconnects there at all. I will probably shoot the dye in there and see what leaks I can find. I have had some experience in replacing seals. I helped a friend replace a pinion seal in an old Suzuki Trooper but that was when we were both in the USAF and most military posts had an auto/body shop you could rent for literally a few dollars a day and had access to lifts, air tools and hydraulic presses - anything a budding backyard mechanic could dream of having. But now I have only a few tools and a bad back, a low patience factor and a very low budget so this help here has been tremendous. Again, your experience here has been very much appreciated.

 

[Lube]

@Lube - Thanks for the advice there. The compressor looks clean around the clutch, pretty much all over really. I don't feel any oily residue on or near the compressor. I have a sinking feeling it's coming from the condensor area. I haven't really looked at it closely in this area and don't know if there are any quick disconnects there at all. I will probably shoot the dye in there and see what leaks I can find. I have had some experience in replacing seals. I helped a friend replace a pinion seal in an old Suzuki Trooper but that was when we were both in the USAF and most military posts had an auto/body shop you could rent for literally a few dollars a day and had access to lifts, air tools and hydraulic presses - anything a budding backyard mechanic could dream of having. But now I have only a few tools and a bad back, a low patience factor and a very low budget so this help here has been tremendous. Again, your experience here has been very much appreciated.

I put that the way I did for a couple of reasons. The pinion seal you replaced doesn't bear much resemblance to a mechanical seal (in fact the only resemblance is that they are both called seals). Like I said, if you don't have experience with a mechanical seal, as opposed to the lip type seal in a rear end, then I wouldn't recommend going it alone. You might get lucky, but the odds aren't good. A fingerprint in the wrong place on a mechanical seal creates expensive junk.

 

[deanamal]

@Lube

Yeah, I don't think I want to attack that issue concerning the seal. First, I know absolutely nothing about compressors and I have don't have the proper tools. I used to SCUBA and worked at a dive shop and had to help tear down a compressor and work on dive regulators and such. This was all small stuff using silicone o-rings and seals with silicone grease - delicate stuff but nothing extra-critical. If I have to, I'll just shell out the dough for a rebuilt compressor and go from there. Thanks for the advice.

It's funny I mentioned pinion seal. I just today saw that my pinion seal is leaking - great...

 

[deanamal]

A/C Problem diagnosed

@Lube - it looks like you hit that nail on the head. My friend came out with a sniffer wand and put a can of freon into it and we heard this gas leaking out at the compressor clutch. He put the wand there and sure enough. It leaked out as fast as he put it in and told me that it looked like a shaft seal. Before he came out, I had noticed fresh oil on the hoses that run perpendicular to the a/c clutch. Well, looks like I'll be shelling out for a rebuild. Thanks for the help.

 

[drdoom]

Always good to see a resolution in these threads...thanks for posting.

 

[ranger7ltr]

You can replace the shaft seal...

@Lube - it looks like you hit that nail on the head. My friend came out with a sniffer wand and put a can of freon into it and we heard this gas leaking out at the compressor clutch. He put the wand there and sure enough. It leaked out as fast as he put it in and told me that it looked like a shaft seal. Before he came out, I had noticed fresh oil on the hoses that run perpendicular to the a/c clutch. Well, looks like I'll be shelling out for a rebuild. Thanks for the help.

And the cost of the seal kit is a lot lower than a rebuilt compressor...All you need is the seal kit and a pair of snap ring pliers and some time to replace it... You could also replace the compressor body o-rings if you needed to at the same time...

If you can find an a/c rebuilders shop you can get the seal kit from them and replace it... I have a teardown of the Ford compressor to see a step-by-step if you want...I even have a used compressor in my garage if you are interested but I would recommend using what you have if it is in good condition...

 

[deanamal]

@ ranger7ltr

If you could be so kind to send me that tear down procedure, I sure would appreciate it. I sent you a message to that effect. I want to thank everyone on this forum for their help and their advice. Very much appreciated.