'88 DL Air Conditioning, Climate Control Problems.

[agzmdv1]

I have a 1988 DL, excellent shape, under 67k miles (really).  This car sat for nearly 10 years mostly inside, some outside, and under a carport. It was just started and driven a couple of times a month.  Lots of TLC has revived this little gem into my daily driver.  Just recently, the R-134 converted A/C compressor and blower cuts out and just stops working while driving. None of the selector buttons or fan speed switchs work.  Ocassionally, it will turn itself back on only to stop again the next day.   I checked all fuses both under the drivers side dash and the two relays and fuse behind the passenger side strut tower under the hood.  All check ok per the Haynes manual I have.  I've not pulled the blower resistor block yet because when it does come back on, all fan speeds function.  I have disassembled the dash and glove box area and removed the stereo looking for an additional relay that is mentioned in my Haynes manual, but can not locate it.   Other than this invisible relay, I'm running out of ideas.   Anyone had similiar problems? Could it be the selector button switches?  I hear the vacuum system moving duct levers when the buttons are pressed.  Is this something simple that I am overlooking or over analyzing?  Any and all suggestions will be greatly appreciated.  Thanks.

[stratman977]

The buttons are vacuum actuated. The vacuum line runs to a white canister (check valve) on the passenger side firewall and then goes along the hood lip to the driver side then through the firewall. Mine wasn't working and I had a vacuum line pop off on the egr solenoid which was causing low vacuum elsewhere. I used a mityvac tester and pulled vacuum at various places in the line until I found where it was leaking.

 

I would pull the dash cover off that goes around the gage cluster and see whats going on behind the switches and then go from there. The don't give you any extra hose, cable and wire to work with back there so maybe someone was in there and pulled the connections apart.

[somick]

The buttons are vacuum actuated. The vacuum line runs to a white canister (check valve) on the passenger side firewall and then goes along the hood lip to the driver side then through the firewall. Mine wasn't working and I had a vacuum line pop off on the egr solenoid which was causing low vacuum elsewhere. I used a mityvac tester and pulled vacuum at various places in the line until I found where it was leaking.

 

I would pull the dash cover off that goes around the gage cluster and see whats going on behind the switches and then go from there. The don't give you any extra hose, cable and wire to work with back there so maybe someone was in there and pulled the connections apart.

Even with little vacuum the blower still should run blowing air from the center vents.

 

There should be some kind of switch that turn the blower motor on when any button is pushed.

 

Regards,

Sam

[agzmdv1]

 I've checked all the vacuum lines in the system, and all appear intact without loss of vacuum.  Still searching for that last stealthy relay.  I'm beginning to think it is electrical in nature.  The blower works when 12v is directly applied.  Going to start chasing wires from the selector switch and fan speed selector knob.  The wiring diagrams from the Haynes manual I have are decent, but rather vague since they attempt to cover multiple systems over multiple years.  Thanks for the suggestions Stratman and Somick.  Open to any and all ideas.  Thanks again everyone.

[agzmdv1]

Ok, still no joy on the a/c blower or compressor coming on.  All fuses in the fuse block check ok.  The cluster of four round relays above the fuse block all click when the ignition is turned to run except one, but swapped it with one next to it since they are the exact same part number, and the relay itself checks ok.  Don't know what circuit this third of four relays is for, since my wiring diagrams aren't that accurate.   On the passenger side behind the glove box, I've checked the blower motor resistor and all coils show continuity. The blower motor isn't getting power with the switch, but does run when directly jumped.  There was one other round relay in the wiring bundle above the glovebox, same part number as the cluster of four above the fuse block,  was not clicking when ignition turned on.  Again swapped it into a known clicking one, and it does indeed click.  As stated before, chased all vacuum lines to and from the selector switches. No leaks, and can hear dampers move when buttons are pushed.  The two square relays behind the passenger side strut tower and its fuse check ok.  One thing puzzles me though, there is a small circuit board on the pushbutton selectors.  Only three wires are connected to it, a solid green, solid yellow, and a solid black.  The black one I presume is a ground to the three lights on the selector block.  The green one reads 12v with the ignition on and selector off.  Yellow reads 0v.  When any other button besides off is pressed, the green one goes to 0v, yellow remains at 0v.  Is this normal?  Is this where my problem is?  Don't want to jump these wires for fear of damaging something.  Any and all idea will be appreciated.  Thanks.

[Goldenhands57]

 I have the exact same year and make. My DL is a wagon. The A/C system has a switch in it that protects the compressor if the charge pressure is too low. The switch I mention is in the high pressure side of the system in the Subaru design. Make sure your R-134 is to pressure spec. To charge the system after evacuating the system it is required to over-ride the low pressure switch. Simply jumping directly to the positive of the battery will do the trick. Do not drive the compressor for a long time by direct jumping to the battery because you could overheat the compressor if there is not enough oil to protect the seals.  Do not jump the wires on the small circut board you mention! No need to do that. It is also possible the magnetic sensor on the clutch is not close enough to the clutch. The "three fingers" should be around 2mm from the A/C pickup sensor.  The fact that somtimes you do have compressor and then it "clicks off" indicates to me that the refrigerant charge is too low or the switch to detect the pressure is defective. The system is trying to protect itself as designed.