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A/C electrical problem: '85 RX


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I'm trying to square a few things away on the RX before Mykingcrab takes possession.

I've replaced a blown o-ring in the compressor, vacuumed it down, and tried to charge it up. The compressor won't stay on for more than a second. I thought perhaps it had a bad low pressure switch. Jumping the switch did nothing, aside from turning the compressor back on for just a second. The relay behind the right shock tower clicks when the switch is jumped, clickes again a second later when the compressor switches off, and clicks again when I remove the jumper. It's almost like something is purposely turning the compressor off.

A little research lead me to the compressor lockup sensor (you could call it that, I guess). Alldata suggests that if the compressor locks up, this sensor will see it and turn the compressor off. I have two of these, neither one makes a difference.

 

After putting a jumper wire in right at the relay, I was able to get the compressor to stay on, and I charged the system and determined that it worked. yay. Anyone have any suggestions on the electrical side of the house?

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is everything with the belt protection system working properly?

there should be a coil pickup on the front of the compressor - if it is not close to the tines that spin, the compressor will automatically be disengaged after a few seconds of running

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theres a little black box somewhere under the passenger side of the dash - that is the "pulse amplifier" it intervenes in the compressor cycle if belt slippage is detected - it connects to the ignition coil (-), and the pulser assy - and is between the low pressure switch and relay - if it was completely missing, nothing would happen - sorry I dont have access to a scanner, or i'd scan it as I have the FSM - the gap does not have to be exact - as close as you can comfortably get to the compressor tines, without touching is how I always measure it - I'm trying to find the exact measurement now

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actually - the pulse amplifier seems to be the "brain" of the A/C system - there also seems to be provision in it for the thermal sensor on the evaporator, and all those other goodies that keep the AC system from getting overloaded (it must cycle) - I would be surprised if the pulse amplifier is faulty, as the system did cut on for a little while - are you shure you are jumping the low pressure switch, and not the fan switch? theres another switch right nest to the low pressure switch to detect that the pressure is high enough that the fan needs to come on

 

one thing I forgot to mention - make shure you dont overcharge the system (esp. if you are using 134a) - you will have the Matsu************a compressor stock, which is more efficent (doesnt slow your car down), but less reliable than the hitachi - so just charge until you get cooling - I blew the compressor the first time I tried (seal went) - actually, my current system is running on regular mineral oil, with EnviroSafe refrigerant - it is not 134a, but it is perfectly legal for non-professional use, and it seems to work very well, Ive had this setup on my car for over a year now, with no problems - I did have to order it offline - its made somewhere on the west coast.......

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It does the same thing with both switches, all combinations.

 

Here's a question...if a fan wasn't hooked up, would the amplifier detect it? The fans aren't stock, they are modine's (I think), one isn't wired up correctly.

 

My lack of accurate diagrams aren't helping. Alldata doesn't really differentiate between the models very well.

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fans dont really matter (mine is bypassed from it anyway) - just that pulser assy - if you have the pulser (the pickup I mentioned) hooked up properly, and the pressure switch bypassed, you shouldnt have an issue (unless the relay or pulser unit is bad) - there is a thermal protector switch as well (yours is Matsu************a) located on the compressor as well, but if that was open, the compressor wouldnt even engague in the first place...... - if someone has the diagrams AND a scanner, I hope they scan the diagram - I have the diagrams, but no scanner, or digital camera

 

edit - ammusing - I guess there is a new censory thing - OK - I'll just call it Panasonic - I was using the "Subaru" name for the system...... the word it is filtering is the japanese name for the company anyway...... I dont know why Subaru uses it

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Maybe I have 2 bad pulsers. Doesn't sound likely, I guess I need to break out the ohmmeter.

hmm - check the system with an ohmmeter - theres a thermal cutoff on the compressor too (should be closed, no resistance) - and I agree with Cougar that the magnetic clutch may also be an issue - another thing that could be the problem is the control module itself - but I think it is a pain to get to, so you want to avoid it if at all possible

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NUG IS THE THE MAN:banana: DUDE WAY TO GO,THANKS A MILLION FOR EVERYTHING.COUPLE WEEKS AND ILL BE ABLE TO GET TO VA. TO GET MY WELL CARED FOR SUUBBBYY. :burnout: :burnout: :burnout: THIS ONES COMING TO A GOOD HOME ,CANT WAIT TO GET OUT OF THIS FREIGHTLINER AND ONTO A JETLINER,AND RX IT HOME TO MISSOURI. USMB BE THY NAME. THNX :D

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