AC driving me nuts

[dickdowning]

Hi folks,
I'm going nuts with the AC in my 1995 Eddie Bauer Explorer with the Electronic Automatic Temperature Control. This spring I had a shop replace the low pressure switch, the compressor and clutch, the Accumulator/Drier, and the Evaporator Core Orifice. They flushed the system. They pulled a vacuum and let it sit for about 30 minutes to make sure there were no leaks add new oil and freon and everything worked beatifully until about a month ago. The air just quit working. I jumpered the low pressure switch nothing happened. I pulled the compressor clutch connection and there was no voltage. I even disassembled the clutch connector and tightened the clips to insure a good contact. Still no air. I ran a jumper from the battery positive to the clutch positive and the AC started up fine and cooled things down to frigid. It had cooled off down here in Texas so the temp was only about 68 degrees. I put the gauges on and non running they showed 68 psig pressure before I started which is about right for 134a. I jumpered the clutch and got 28 to 30 on the low side and 150 on the high side. I checked any fuse that was related to the heater or AC and they were fine. I open the power distribution module under the hood and found the the WOT relay that shuts the ac down when passing was hot. I could feel it cycling on and off every 1 1/2 or 2 seconds whether the sytem was jumpered or not. I replaced it but the new relay did the same thing. When I first looked at it in early September (95 degree ambient temperature) it did start running a couple of times on its own but only ran for a minute or so each time. When I worked on it this week a few minutes after I started working on it in 70 degree ambiant temps it ran okay for about 20 minutes after I jumped it and got it running. I pulled the jumper and it kept running okay. It quit and won't start on it own again the last couple of days. The EATC unit has a self test setup. You press the "off" and "floor" at the same time and then within 2 seconds you hit "automatic". A little revolving box tells you it is working and then it is supposed to show the error code on the display when it gets finished. I ran it several times and when it finishes it comes up with the same 888 display with all the functions e.g. floor, defrost, panel, defrost lighted and all the other stuff that comes up when you first turn the car on. There is no error code shown on the display. The Ford truck CD seems to indicate the error codes show up on the normal EATC display but I notice that there is what appears to be a code reader plug under the dash to the left of the steering wheel. Is there a code reader that has to be plugged in to that to read the codes? One last thing I noticed. If I pull the wot relay out of the power module while the car is running the idle increases about 25 0r 30 rpms and drops again if you plug it back in. Can any one think of something that can be causing these symtoms. OBTW the heater and all the floor, vent, panel, blower switches work fine.
Thanks for reading this novel but I wanted to give as much info as I could
Dick Downing

 

[rwenzing]

The Ford truck CD seems to indicate the error codes show up on the normal EATC display but I notice that there is what appears to be a code reader plug under the dash to the left of the steering wheel. Is there a code reader that has to be plugged in to that to read the codes?

For most Explorers, EATC fault codes can be read one of two ways. First is as you described using the self test. If the EATC says 888 at the end of the self test, then there are no faults being detected. The second is via the Data Link Connector under the steering column using a special dealer diagnostic tool. However, the 95 EATC was not wired that way, so the second method would not work on your Explorer, even if you had access to the dealer tool. Your only option is the self test.

It is important to know that the EATC self test is for the control unit and its sensors. It cannot detect independent electrical or mechanical failures in the rest of the A/C system.

Here are some things you can check:

• Purple wire from EATC control unit - must be near 12v for A/C
• A/C Cycling Switch (aka Low Pressure Switch) - must be closed for A/C
  Sounds like you may have already checked this
• A/C Pressure Cutoff Switch (aka High Pressure Switch) - must be closed for A/C
  This assumes that your 95 A/C system has one - Ford added this switch to the Ranger/Explorer A/C system sometime in the mid 90s. Look for the Pressure Cutoff Switch on the high pressure line, probably near or on the compressor.
  
  

 

[dickdowning]

pressure cut off switch

Thanks for the reply Bob. I'll check the purple wire. You're correct that I checked the low pressure switch. It does appear to have an AC pressure cut off switch on the compressor. I tried to get the connector to let go so I could check it but just broke off one of the tabs that appear to hold it on. Is there some secret to unplugging the connector without totally destroying it? I previously was using a small jeweler's screwdriver to gently pry the tab up when it broke.
Dick

 

[TheJackal]

Connector's probably brittle from all the heat under the hood.

AFAIK, the WOT relay is activated by the PCM. So it seems to me, the PCM keeps trying to shut off the compressor, perhaps because it's getting a bad reading from the engine or something? Might be something to consider there.

 

[ma96782]

You said..........

I jumpered the clutch and got 28 to 30 on the low side and 150 on the high side.

That ain't right.

IF I were you......I'd be going back to the basics. I remember once being told that I should be looking to have at least a 150 psi difference, between the two readings.

Perhaps, looking to get the pressure up........might be low on R-134a (leaked out a bit, but your static pressure seemed good).......or, might be bad compressor. BTW.....my sticker that said how much R-134a should be in the system.......was wrong. Who's fault......the engineers or was it that assembly line guy? Labor and management question.

FOR THE RECORD.........I didn't stay at a Holiday Inn last nght.

Aloha, Mark

 

[dickdowning]

134a Pressures

Thanks for the info but we were having a cold stap down here in Texas and the temps were only running about 70 degrees so that brings the readings down. Had it been 95 or 100 like the week before the highside would probably have been up there. The pressure when it is not running and is at 68 degrees ambient is supposed to be 68.5 and mine was running 69 so I think I'm okay on 134A.