Hi, I wonder if anyone has seen this problem: With the air conditioning turned on the compressor engages for about 1 second, then disengages. This is repeated every 5 to 10 seconds.

I have a 97 Explorer with 162K miles on it and this just started today. The car was parked in my garage for a few days; worked fine last week!

I wonder if it's sensing that there is no pressure in the system?

Thanks,

Joe

 

Hi Joe,
Sounds like you have the problem figured out. A sensor will not allow the compressor to damage itself if it is low on refergrant. Go to your local autozone or other parts place and get a R134 recharge kit. This contains coolant with compressor oil, and o-ring softener (leak stop) all in one can. Get a kit with a hose and gauge. The gauge will have red, yellow and green zones to assist you in telling how much coolant to put in. Cost about $20 and easy to do. It will come with all the instructions. Your suction connection is on the left side of the engine by the evaporator/dryer.
Good Luck,
Chuck

 

Thanks for the quick reply, Chuck! I'll try this out and let you know how it works out.


Joe

 

OK, next problem.

I bought a recharge kit and put 2 cans of refrigerant in. Worked OK, but I wanted to see if I could get more cooling... since the pressure was about 30 psi and should be 45 according to the kit instructions.

So I put 2 more cans in and things seemed to work OK. Still didn't get up to 45 psig though.

A couple of days later, NO A/C. This time the compressor is not engaging at all.

The relay seems to be OK, I swapped it with the fuel pump relay - no soap.

I believe the relay is being energized since I feel it clicking when I pull it out of its socket.

The compressor clutch connection I believe is on the lower outside of the compressor by the pulley, right? The one I can't get off? I measured about 5 ohms resistance to ground so that tells me that the coil is OK. Just not getting any volts.

Questions:

Is it possible that there might be too much pressure in the system and there is a pressure cut-out?

Is there something else in line, electrically, between the compressor clutch and the A/C relay? The only A/C fuse I saw was in the main under-dash panel and appears to be good.

Thanks,
Joe

 

UPDATE:
I tried bypassing the pressure switch on the low pressure side; nothing.

I bypassed what appears to be a pressure switch behind the compressor... nothing

I jumped the clutch coil wire to battery, and the clutch pulls in. So the clutch is OK.

I measured the pressure on the low pressure side with the recharge kit... no pressure to speak of.

Besides getting a new vehicle, is there anything else anyone can think of?

Thanks!

 

Strange that the WOT relay is clicking when you pull it. It should only be open at WOT. The relay is controlled by the PCM. Since it's such a simple thing to do, try pulling the codes & see if that tells you anything.

BTW, heres what the 97 EVTM shows for the "AC clutch cycling switch." "Normally open below 24.5 PSI. & closed above 43.5 PSI."

And for the "AC pressure cutoff switch" "Normally open above 430 PSI & closed below 260 PSI."

Edit, the WOT relay is in the power distribution box under the hood/driver side. Is that the one that you're referring to?

 

Yes, it was the WOT A/C relay, in the plastic electrical box under the hood. I even swapped it with the fuel pump relay to make sure that it was operational.

What does WOT stand for, anyways?

My gut tells me that it's something in line between the relay and the clutch, but I don't have a wiring diagram. On the wire loom under the compressor there is a white band that says "DIODE" which may be in line with the clutch coil. This is the only thing I can think of that I haven't checked, mainly because I can't get the *&(&^^@%$# connector off the compressor!

I don't know how to pull the codes, is the procedure somewhere on this site?

Thanks,

Joe

 

WOT is wide open throttle. When you stomp on it the WOT relay opens the circuit to the compressor clutch & shuts it off.

Thats why it's strange that the relay clicks when you pull it.

Sounds like it's open when it should'nt be.

Since you dont have an OBD-2 scanner, see if Autozone etc will pull the codes.

 

One other possibility, the WOT relay is grounded by the PCM to open it on the Pink/yellow wire. It might be grounded out somewhere.

 

I've by-passed the pressure switch at the low pressure fill port by bending a 12-14 ga wire into a U and plugged it in. This helped me add coolant when the system was very low by running the compressor to draw in the 134a. I assume by your post that you did a similar thing. I also had trouble after recharging a while back, the compressor would run, make a bunch of growling noise and shut off. I found that the recharge cans had stop leak in them. I put 2 cans in and it seems that the stop leak gunked up the system. I accidently left the recharge hose on and some "goop" shot out of the fill port. The growling stopped and the air was cold. That's what lead me to believe that too much stop leak gummed it up. I recently topped off the A/C in my 97 and I quit when the pressure gauge that came w/the kit read 30, dead center of 'good'. Air is cold.

 

Before I wnet about recharging the system, I would have found out where your leak was. The refigerant had to get out somehow. As vicv stated, you may have had a stop leak in the refigerant you purchased and now it's gumming up the works. You may have a bigger problem than what you had originally. I suspect your compressor may have been shot.

My AC system failed last summer. I had the compressor and evaporator core replaced. No problems since. Should be good for another 8 years (7 now).

Good luck with it.

 

I agree w/texan2004, you need to find the leak or you'll be adding 134a all the time. I changed the o-rings in the lines a few years back after I noticed that I could rotate an in-line test port tube without effort.

 

Thanks for all of the replies and hints. However I can't see how the compressor could be bad if the system never tries to engage it. It seems to me to be an electrical problem between the clutch coil and whatever activates it. I was thinking fusible link but I have no idea where to look.

I tried bypassing the high pressure and low pressure switches one at a time but not both simultaneously. Wonder if that would make a difference.

With 163,000 miles on it the car still runs pretty good. Body-wise it is in very good condition but the engine is starting to worry me. It has the SOHC engine in it and yes, it rattles and clacks for a few minutes when you start it but it smooths out eventually. I've replaced the alternator this year but engine tranny and 4wd systems are all original. I just get to worrying about what might happen if the timing belt breaks because of the tensioner issues.

So I'm in a quandry right now, do I put the $$ into it or a replacement? I suppose I'll have to bite the bullet and get the AC fixed, since I intend to keep it around anyway even if I get a newer vehicle (thinking 2003-2005 Explorer incidentally). I live in a rural area and it comes in mighty handy having a spare vehicle when your main drive is at the doctor's office.

Thanks again for your help.

Joe

 

The compressor is a moving part and it too has 163,000 miles on it. It's where I would look first if you are going to do this on your own. If it were me, I'd pay the AC guy to locate the leak and troubleshoot the compressor engagement problem then decide how to fix it (you do it or have him do it). It will save a bunch of time and perhaps some money. HYope you get it straightened out soon. Nobody likes a broken AC in August.

 

Well, all the facts are now in...

I took the car to the shop. The mechanic evacuated the system and held the vacuum to see if there were any leaks - it held vacuum for 15 minutes so, no leak.

He charged the system and - voila - air conditioning. He also put some tracer dye in to double-check for leaks. His leak tester showed a leak near the cylindrical object under the fill port - is this the accumulator? Dye testing showed all kinds of leaks in the accumulator. The accumulator (is that what they call that thing?) was rusted out and about to pop anyways, and I may have speeded this up by overcharging the system.

Replace accumulator, re-charge system, look for more leaks - next on the list of leakers is the evaporator.

That's it, I said - no more work done here.

He charged me only for the part, no labor. Great guy.

So I guess I'll be driving with the windows open until the snow flies and/or I get a newer vehicle. Or I break down and spend another $500 to have the evaporator replaced.

Thanks to all who have contributed to this thread. I wanted to follow up with how this story turned out.