1971 A/C Problem (RELAY)
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Pro
Joined: Apr 2002
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From: dripping springs tx
1971 A/C Problem (RELAY)
I started working on the a/c and found a bad a/c relay. Listed on the wiring diagram it is called a blocking relay. It is the a/c relay that supplies power to the compressor.
Does anyone know the part number and where I can get one?
Does anyone know the part number and where I can get one?
Team Owner
Joined: Jun 2000
Posts: 38,923
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From: Southbound
Cruise-In II Veteran
The '71 assembly instruction manual (AIM) should show the relay and it's original part number. It's possible the part number subsequently changed, but the original number should give you a starting point.
Safety Car
Joined: Oct 1999
Posts: 4,101
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From: NorCal
Creative thinking...
I found an A/C relay ("high blower relay") from a '72 Caprice that was identical to mine ('69) at NAPA. Don't have a part number, but it was also a third of the price the specialty guys wanted for the OEM replacement.
Hans
Hans
Racer
Joined: Apr 2005
Posts: 339
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From: San Diego CA
Yes, the blocking relay is different than the blower relay. As I'm guessing you've learned, the blocking relay is next to the anti-dieseling relay, and both are located behind the passenger's side dash pad in the interior of the car.
Both the blocking and anti-dieseling relays are used by the a/c system to control when the compressor kicks in.
The anti-dieseling relay engages the a/c compressor when the ignition key is turned off. It does so to add drag to the engine in case it experiences dieseling after turning off the car.
The blocking relay ensures that power is applied to the compressor if the a/c controls are powered.
Both of these controls are simple SPDT relays and can be replaced with aftermarket relays...unless you're a purist.
Both of mine went bad long ago, and now I don't even use a blocking relay, and my anti-dieseling relay is bypassed.
Good luck...
Both the blocking and anti-dieseling relays are used by the a/c system to control when the compressor kicks in.
The anti-dieseling relay engages the a/c compressor when the ignition key is turned off. It does so to add drag to the engine in case it experiences dieseling after turning off the car.
The blocking relay ensures that power is applied to the compressor if the a/c controls are powered.
Both of these controls are simple SPDT relays and can be replaced with aftermarket relays...unless you're a purist.
Both of mine went bad long ago, and now I don't even use a blocking relay, and my anti-dieseling relay is bypassed.
Good luck...
Race Director
Joined: Sep 1999
Posts: 11,358
Likes: 379
From: Plano TX
SoCal: Not sure what you're saying here... you're not running a blocking relay and run all the current straight through the microswitches on the control head??? I would think they'd burn running 5A through them?
You can replace the blocking relay with a standard Bosch automotive relay. I posted the wiring a few months back. I don't know of a simple way of replacing the anti-dieseling relay. A regular SPDT relay won't work.
You can replace the blocking relay with a standard Bosch automotive relay. I posted the wiring a few months back. I don't know of a simple way of replacing the anti-dieseling relay. A regular SPDT relay won't work.
