AC Relay
06-13-2009, 10:06 PM
#1
Instructor
Thread Starter
AC Relay
Howdy. Things have been going so good with my project 928 since replacing the exhaust, that I haven't posted in a while. Been finding helpful things in previous posts, but mostly just doing cosmetic things lately. Even got the original clock working! And finally started giving my daughter her driving lessons in it.
But now I have a quick question about the AC relay. My AC was working great after a recharge and fixing a couple broken wires. But now it has become inconsistent--comes on nice and cold at first, then starts to short cycle. And now today it won't come on at all. I have found some great info from other posts, and I think the only thing I haven't ruled out is the AC relay that folks say is very susceptible to failure. So my question is....where exactly is this relay? On my '82, is it actually inside the HVAC module? Or somewhere else?
FYI...I've verified proper pressure, tested/jumpered the pressure switch, tested/jumpered the freeze switch, and made it work by hot-wiring power to the compressor clutch and idle valve (nice and cold).
Thanks!
But now I have a quick question about the AC relay. My AC was working great after a recharge and fixing a couple broken wires. But now it has become inconsistent--comes on nice and cold at first, then starts to short cycle. And now today it won't come on at all. I have found some great info from other posts, and I think the only thing I haven't ruled out is the AC relay that folks say is very susceptible to failure. So my question is....where exactly is this relay? On my '82, is it actually inside the HVAC module? Or somewhere else?
FYI...I've verified proper pressure, tested/jumpered the pressure switch, tested/jumpered the freeze switch, and made it work by hot-wiring power to the compressor clutch and idle valve (nice and cold).
Thanks!
06-13-2009, 10:09 PM
#2
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Join Date: Jun 2001
Location: Ashburn, VA
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Inside the HVAC module. The only trick to replacing it is that there isn't a readily available relay that will fit onto the circuit board. You have to run wires and mount it externally.
If you need any help with the replacement, send me a PM. I'm just a couple of miles up 28 from you
If you need any help with the replacement, send me a PM. I'm just a couple of miles up 28 from you
06-14-2009, 04:25 PM
#3
Instructor
Thread Starter
Thanks!
Opened it up and found the relay, but it seemed to be working fine. After further troubleshooting, discovered that the pressure switch appears to be short cycling. And verified again that the pressure is good with guages. So...looks like the pressure switch is the problem. Jumpering it for now, while I order a new switch and bottle.
Thanks!
Opened it up and found the relay, but it seemed to be working fine. After further troubleshooting, discovered that the pressure switch appears to be short cycling. And verified again that the pressure is good with guages. So...looks like the pressure switch is the problem. Jumpering it for now, while I order a new switch and bottle.
Thanks!
06-14-2009, 04:40 PM
#4
Chronic Tool Dropper
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Lifetime Rennlist
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Tom--
If it really is just the switch, you can swap in the new one without bleeding any refrigerant. There's a schraeder valve in the switch mounting port to hold pressure while you do the swap.
If it really is just the switch, you can swap in the new one without bleeding any refrigerant. There's a schraeder valve in the switch mounting port to hold pressure while you do the swap.