Been working on getting my AC running. I have the system all flushed, new O rings, dryer, hoses and exp valve and sealed up ready for vacuum test. Looking at the AC relay on the passenger fender and there is a tan and green (cut) on a 2 wire connector and a green on a single conn.

Can someone post a pic of there AC relay showing the terminals and wire colors or a AC wiring diagram PLEASE.

 

I've got a 1971 Cutlass with AC but there's no relay on the passenger side fender. I think the two wire clip may be the one that attaches to the compressor and the single green wire is a ground to the compressor bracket. John

Nope! I got that wrong. Give me a minute and I'll post pictures of what I think your looking for.

 

P1010269.jpg
Here's where the harness meets the firewall AC box. This harness comes from a hole through the firewall near the distributor

P1010268.jpg
The same harness described above but viewed from below, almost spark plug level. It plugs into several forks on the AC box.

P1010267.jpg
Small plug as seen through the hood hinges. The green wire comes from the harness, then goes to the compressor.

P1010266.jpg
Compressor plug, two forks side by side then the ground strap.

Let me know if this is what you were looking for or if there's something else you need. Again, this is a 1971 but I thought it might be the same as 1970. John

 

I think '71 is different?
The attached illustration is from a GM parts catalog, shows 1969-70 F-85 w/ manual air conditioning.
If this is the same the relay on the fender is the "compressor hold-in relay" all it shows.
Maybe somebody here with an AC car can just go look and tell you what color they are.
The wire to the compressor is usually green like in John's pics.

 

That might be what he has. It was used only for a short time, to engage the AC compressor during engine shutdown to help prevent dieseling (run-on)... I cannot remember where I saw the exact schematic...

 

The assembly manual is calling it "compressor hold-in relay" #404422 it also shows 3 wire to it but no colors.

I have the resistor on the evap. housing and the harnes has 2 wires to the relay and 1 green from the relay to the compressor as shown.

I think the green wire that is cut will go the compressor?

 

Strange, my '71 doesn't have a relay on the pass. fender. The Chassis Service Manual shows a single wire (green) running from the resistor to the compressor clutch connector. Any chance this relay was added later on? I'll take a peek at a buddies '70 442 and get back to you..

 

I'm no A/C guru, but I believe that 1971 was the year they got rid of the hold-in relay and added an overheat function (I hope I got that right) which cycled the compressor. 1970 and earlier ran the compressor full-time (once it was turned on). Which begs the question: are you sure you want your compressor to work like that? I modified my hold-in relay so that the compressor turns on AND OFF simply based on the position of the dash control.

 

Here is what I'm dealing with, after looking closer the relay above the break booster has no wire to it, they are cut short (black/yellow, blue, purple) Need help with where the go in the relay.
My fan switch inside has high on the bottom and low on the top maybe due to all wires to the fan relay are connected to each other.

I think the relay on the finder is OK, and will extend the cut green to the AC comp.

Unable to upload pic's will try later.

 

The fender relay is a hold on relay...if you ground the case of the relay and put 12 volts on one of the terminals and the relay clicks then that is the signal wire which should come from your dash control...then one of the other two terminals is the 12 volt supply for the clutch and the other is the green wire 'to' the clutch...it doesn't matter which of those wires is on either of those two terminals...it is just a high power switch...The fan switch might be mounted upside down...The relay above the booster is for the high speed blower and is fed power by an inline fuse near the horn relay -brown wire-short 30 amp fuse- there are no wire colours shown in the book-one wire on the blower relay will be brown, one wire will go to the blower resistor on the heater case and the other wire will go to the dash switch (yellow?)

 

Here is the pic's

Thanks for the help. I'm learning.

 

Attached are the wire that need to go to the blower relay. What color wire go's to what post on the relay? And I need power from the horn relay right? to the lone pin and the 3 others to the other 3 pins.

Love to find the last owner and take his wire cutters away.

 

Low speed is yellow from switch to red resistor junction; medium is blue and the two colour wire is high on non A/C cars but probably uses same wires on A/C car...and the high blower speed comes from the blower relay over there...same deal with that relay- ground the case and see which terminal makes it click then that wire comes from the high speed terminal on the dash switch...brown w/ inline fuse to the other terminal and it looks like a big fat black wire that shows on your # two pic...so that is direct 12v for high blower...anything more specific will take time for me to look at a couple of cars ... BTW an A/C switch has four speeds and three for non A/C.

 

My 68 has the relay on the pass fender. Can you tell me which two wires are in the double connector and which terminal goes to the compressor? The wire harness from the firewall had the terminal end cut off, and the comporessor wire was missing.

 

In that picture of you holding the relay, I'm guessing that if you put 12 volts on the single green wire plug that the relay will energize and therefore the other two wire plug will have the green wire go to the compressor and the brown wire to the 12 volt supply which is coming from the heater control....or the other way around-put 12 volts on the green wire in the two wire plug and if it energizes the relay then the single wire plug (green) will go to the compressor and the other two wires go to the heater control...The chassis manual shows the harness and it's routing but not the colours or specifically the fender relay... OK...so I went out and looked at my '69 Vista and it's the same as a '68...so the green wire in the double plug goes to the compressor and the other two wires go to the heater control...

 

THANKS for the responses!
The relay on the finder is a hold-in relay to make the compressor run full time when the controls are on AC. I ran a 12V 30A wire from the horn relay for power to the compressor on the common side of the relay, 12V from the controls to the coil, compressor lead to N/O and the ground for the coil I switched in the cab to have ability to switch the system off if needed.

Flushed the system (not the muffler) and pulled a vacuum and let it sit for 5 days waiting for the refrigerant to get here (no leaks) repulled vacuum last night and filled with Enviro-safe Hydrocarbon refrigerant R12 replacement. System pressures were good and vent temp at 36-40.

Went for a ride and enjoyed the cool air. Sure effects the engine temp I may install a electric fan in front of the evap to help push air when the AC is on.

 

This is pretty helpful

 

I guess I missed this when it was first posted but this may help. It also appears in the photos that the Hold In relay is mounted by the brake booster and the High Speed Blower relay is over near the passenger fender. If so, they need to be swapped. The attached photo shows the blower relay and wires which is mounted near the brake booster.

I might have a spare AC harness that will solve the wiring issues if you would be interested.

https://classicoldsmobile.com/forums...-function.html

Brian

 

I ordered new under hood wiring harnesses. Cleans everything up and it looks much nicer. Ordered them from The Parts Place. I'm restoring a 1968 Cutlass Supreme Holiday Coupe. Mine is number 1242 off the assembly line in Fremont. My car originally did not come with the compressor hold in relay. Take care.