EA82 HVAC Question

[88SubGL]

I have a 1988 GL 4WD d/r wagon that I bought back in May. The clutch was bad, so I pulled the engine to replace it and resealed the engine from the head gaskets up. Also replaced all 7 coolant hoses. Thanks for the various tips found here to accomplish this. 

Now the question: I’ve just started driving it and found that no matter which hvac button I push, the a/c compressor engages. Is this normal? I know on most cars, when you turn on the defrost it comes on but not in the other positions, except for the a/c of coarse.

 Thanks for any insight on this.

[DaveT]

It is normal if it engages for a few seconds and then releases in not ac modes.  My 86 did this always compressor  running thing.  It came with a worn out compressor.   I investigated the schematics, etc. And found that some genius had added a wire to force the compressor to run in all hvac modes.  I removed the wire, and it only ran in ac and defrost.  It also released if you hit the gas when at a stop, to free up power for acceleration.   All my newer ones functioned similarly.   Some didn't have the unloader relay though. 

[88SubGL]

Thanks for the reply. So was the “genius” the previous owner or the factory? If the factory, was the wiring at the switch or under the hood? I’m guessing at the switch. My compressor was running the entire time the heat was on. 

[DaveT]

Not sure.  But it was a real hack job.  A wire was run to a bolt that mounted something under the dash.  Just stripped and wrapped around the bolt, bolt tightened down.  Too long ago to remeber- this was in 1988 - but the wire either tricked the unloader so it was always on, or parreleled it to cause the always on.  Other thing to check is a microswitch in the heater vent mech.  Really need the fsm to see all the details.

[88SubGL]

Thanks. At least I have a direction to go. I’ll check out the fsm.

[88SubGL]

So I don’t have the part of the fsm that shows the dash wiring, does anyone have a scan from the fsm or know where I can find one? I would really like to see how the hvac is wired. Thanks 

[Subasaurus]

i asked this a few years ago and supposedly it's to cycle things around everyonce in a while, i didn't buy it.

i just put a manual switch to turn the A/C On and Off, much more freedom, i could redirect the air wherever i pleased, if i wanted my legs to be cold but not my arms, i could override the A/C to come on even though it wasn't suppose to... just a thought.

[88SubGL]

Not a bad idea.

[DaveT]

Part of the normal operation is a momentary run on start up of any hvac mode.  On cars in this age it was common, not just Subarus.

 

[DaveT]

The hack job wire I found on my 86 was wired to keep the AC relay energized all the time, so the compressor ran in any hvac mode except off.   I was unaware of the mod when I first replaced the compressor, so I added a switch to turn the compressor off manually.

When I eventually got a second similar car, I immediately noticed that the compressor would switch off when I hit the gas from a stop, helping noticeably with acceleration.  Investigating that function was how I discovered the hack modification on the 86.

[Subasaurus]

16 hours ago, DaveT said:

When I eventually got a second similar car, I immediately noticed that the compressor would switch off when I hit the gas from a stop, helping noticeably with acceleration.  Investigating that function was how I discovered the hack modification on the 86.

factory installed 80's A/C compressors are suppose to cut off if you floor it to give you that extra amount of power incase of an emergency, i don't think Dealer added ones ever did though, i know 90's Subaru's do this too.