A/C time delay relay

[Ray70Chrg]

This relay is supposed to let the a/c compressor run for 2-10 minutes when heat or defrost are selected and ambient temperature is 25 degrees or more. My compressor is not being shut down and I stopped after 25 minutes. I'm thinking about just disconnecting the 12v lead and doing without it. NOS replacement is $245 or so and living here in the Phoenix area we do not usually have very humid conditions. Any good reasons to NOT do this? Thanks

 

[LowBikeMike]

Most just disconnect the relay without adverse effects. It can be checked with an ohmmeter amd vacuum pump off thr car. Have you taken it apart to inspect?

 

[Ray70Chrg]

Most just disconnect the relay without adverse effects. It can be checked with an ohmmeter amd vacuum pump off thr car. Have you taken it apart to inspect?

I'll be taking out the center console tomorrow to get at it. Don't remember how hard it is to disconnect it while the whole assembly is installed. I completely rebuilt the heat/ac box several years ago and just recently replaced all a/c components in the engine bay everything is working well except I noticed today that the relay is not turning off the compressor after the allotted time. I let it run for 25 minutes and then shut it down. Thanks for responding.

 

[LowBikeMike]

What model vehicle? My 69 b body is easily accessible under the dash passenger side. I doubt the console would need to be removed.

 

[F4R/T]

Take the cover off below the glove box.

 

[pnora]

This relay is supposed to let the a/c compressor run for 2-10 minutes when heat or defrost are selected and ambient temperature is 25 degrees or more. My compressor is not being shut down and I stopped after 25 minutes. I'm thinking about just disconnecting the 12v lead and doing without it. NOS replacement is $245 or so and living here in the Phoenix area we do not usually have very humid conditions. Any good reasons to NOT do this? Thanks

Read the FSM and get the real description of its function?

 

[LowBikeMike]

Read the FSM and get the real description of its function?

What am I missing, he's pretty much got it word for word from the GSM?

 

[pnora]

What am I missing, he's pretty much got it word for word from the GSM?

It sounds like he does not want to buy the 245 dollar relay. So if it is not working why worry about it. There is a simple procedure that takes a second to do and the compressor will not run. You do not have to disconnect anything.

 

[Ray70Chrg]

What am I missing, he's pretty much got it word for word from the GSM?

Thanks for that reply. Got the a/c delay relay out today and tested it with a vacuum pump. As you know, the relay contacts are normally closed and suppling + 12 to the compressor when Heat or Defrost are selected. After 2-10 minutes the contacts open, turning off the compressor and it will continue off as long as engine maintains vacuum. After the engine is off, the relay contacts will close after 10-15 minutes. Bench tested the delay relay and it works as it should. It took 17 in. of vacuum after 3-4 minutes to open the contacts and roughly 10 minutes to reset to closed contacts after vacuum was removed. Works perfectly as designed, my problem is the engine is only providing 14 in of vacuum because of the cam I have.

Thanks to all.

 

[pnora]

Thanks for that reply. Got the a/c delay relay out today and tested it with a vacuum pump. As you know, the relay contacts are normally closed and suppling + 12 to the compressor when Heat or Defrost are selected. After 2-10 minutes the contacts open, turning off the compressor and it will continue off as long as engine maintains vacuum. After the engine is off, the relay contacts will close after 10-15 minutes. Bench tested the delay relay and it works as it should. It took 17 in. of vacuum after 3-4 minutes to open the contacts and roughly 10 minutes to reset to closed contacts after vacuum was removed. Works perfectly as designed, my problem is the engine is only providing 14 in of vacuum because of the cam I have.

Thanks to all.

You can bypass the a/c running when on defrost or heat in one second without any mods.