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My A/C compressor hold in relay mounted on the passenger fender requires a slight tap on the side to activate the compressor. This isn't a big deal when parked and I have the hood up, but a royal pain in the rear while tooling down the highway. Pulling over, raising the hood just to give that relay a slight thump is a drag.
Question.. Can I disassemble this relay and spray some contact cleaner amongst the internals and fix this sucker? Having reviewed the archives, I gather this part is not readily available and kinda pricey if found..
The previous owner installed a toggle switch inside the cabin to cut the power to the clutch, but I don't think this has any relevance to my problem. The added switch works fine and performs it's intended function without any issues.
A relay that works when tapped on is probably caused by shorted windings in the hold in coil that reduce the coil's pull in power. I'm not sure that cleaning the contacts will help that.
My A/C compressor hold in relay mounted on the passenger fender requires a slight tap on the side to activate the compressor. This isn't a big deal when parked and I have the hood up, but a royal pain in the rear while tooling down the highway. Pulling over, raising the hood just to give that relay a slight thump is a drag.
Question.. Can I disassemble this relay and spray some contact cleaner amongst the internals and fix this sucker? Having reviewed the archives, I gather this part is not readily available and kinda pricey if found..
The previous owner installed a toggle switch inside the cabin to cut the power to the clutch, but I don't think this has any relevance to my problem. The added switch works fine and performs it's intended function without any issues.
tc
There's a thread on here "somewhere" regarding that particular relay - I researched it some time ago. IIRC, many folks simply bypassed that relay for at least one particular reason. Try searching using my Username...I'll see if I can dig it up for you. This may not be a solution, but I recall reviewing at least one thread regarding that particular relay located on the inner passenger side fender.
Found the thread. I cannot speak to any recommendations regarding information contained w/in the thread...but I found the discussion (for what it's worth).
Unless your going for a concours restoration, it isn't needed. Contrary to the application listed above, Olds quit using them after 1970. They would keep the compressor clutch engaged even after you shut the a/c off. When I worked for the dealer, we had people coming in asking us to eliminate them.
So it seems that the solution is to just wire around the relay and rely on the switch contacts in the control head to carry all of the compressor clutch coil's current.
That brings up the question of how much current does the compressor clutch use? I have an old compressor on which I could measure the current when I get home unless someone already knows the answer. Then I would look at the construction of the switch in the control head to see if it will reliably carry that current without shortening the life of it...
If you want to keep the look of the relay but modify it to turn the compressor off when you turn the ac controls off the below thread shows you how to modify the Relay internally. I have done this a couple times and it works like a charm. I don’t like the compressor staying on all the time.
Okay, according to Eric, all I need is a short jumper to connect the green wires on this relay.
"All that relay does is make the compressor stay on even if you turn off the AC. It should be wired around and in 71 Oldsmobile got rid of it because it was not needed. If you want it there to look original is the only reason to use it. If the compressor will not engage because of that relay just take the dark green wire from that relay and hook it to the wire than runs to the compressor clutch (also dark green) and you are good. This way the compressor will turn off when you turn off the switch."
Before I do this, I will take a couple of readings with my volt meter per Joe's precaution. Eric didn't say anything regarding the brown wire going to the relay, I guess I'll just connect it back to the relay to keep it from hanging loose.
Thanks to all who replied here, you guys are a goldmine of knowledge..
TC,
I opened mine up just now and notice that the ground is acquired through a piece of copper that scrapes on the inside of the case. Open yours up and clean where it contacts and make sure that it still has "springy-ness" to it. Since tapping on the side gets it to work, I bet it is this ground strap not making good contact.
Bingo!! I had some corrosion growing inside the case and propagating onto the ground strap spring. I cleaned the strap up with steel wool just fine but the case wasn't cooperating with my efforts. I just rotated the insides 180 degrees to get the strap contact on the clean side of the case and reassembled everything.
I did not cut the white wire because I already have a toggle switch in the car to kill the compressor.
Thanks again to all and especially to Joe V for pushing me to look into the inside the relay.
It is very bent out of shape. It should be fairly close to the other contact, which by the way has a nasty burn spot.
Is that possibly part of the previous owner’s modification to the relay?
Clean the contacts (as Kenneth pointed out) and It is NOT supposed to be like that. Bend it straight to make it look like my picture from my post above.
It is very bent out of shape. It should be fairly close to the other contact, which by the way has a nasty burn spot.
Is that possibly part of the previous owner’s modification to the relay?
To my knowledge, this one has never been opened prior to my effort. It certainly didn't show any evidence at the 6 tab locations. I will pull it back off and get this back to its as designed configuration. I appreciate the help.
tc
Last edited by 4+4+2=10; July 15th, 2023 at 04:03 PM.
Yes! Good to hear you’re gonna get it back to original.
Come to think of it, it really would not work like that. I’m inclined to suggest that upon disassembly, it may have caught on the edge of the shell and got bent then. Since it “worked” before, it had to have happened upon disassembly. It will not work right like that. All the compressor clutch current will go through the control head switch since that bent contact will not do anything now that it’s bent.
Last edited by rfpowerdude; July 15th, 2023 at 04:11 PM.
Yes! Good to hear you’re gonna get it back to original.
Come to think of it, it really would not work like that. I’m inclined to suggest that upon disassembly, it may have caught on the edge of the shell and got bent then. Since it “worked” before, it had to have happened upon disassembly. It will not work right like that. All the compressor clutch current will go through the control head switch since that bent contact will not do anything now that it’s bent.
Don't have any explanation, but it did work after I put it back together. I've taken it back apart and fixed it however. I cleaned the contacts with emery paper...and it still works so I'm good.
Last edited by 4+4+2=10; July 15th, 2023 at 04:58 PM.
July 13th, 2023, 04:53 PM
