A/C Engine cooling fan switch question

[Matt B]

In the high pressure side the A/C system has an engine cooling switch, presumably to switch on the cooling fans under certain conditions.
I tried to find out in the shop manual when exactly this happens but couldn't find anything. I'm still chasing down my A/C issues after r134 retrofit and today recognized that the fans don't run during compressor operation. In my other cars they do as soon as the compressor engages. Thanks!

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[secondchance]

Originally Posted by Matt B

In the high pressure side the A/C system has an engine cooling switch, presumably to switch on the cooling fans under certain conditions.
I tried to find out in the shop manual when exactly this happens but couldn't find anything. I'm still chasing down my A/C issues after r134 retrofit and today recognized that the fans don't run during compressor operation. In my other cars they do as soon as the compressor engages. Thanks!

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If disconnecting the plug at the high pressure switch turns the fan on, switch has gone bad.

[Matt B]

Originally Posted by secondchance

If disconnecting the plug at the high pressure switch turns the fan on, switch has gone bad.

Yun, I don't know if it's appropriate to state it that clearly - but I think I love you [emoji1787]

Seriously, after helping me out with the amps this was the second breakthrough advice! I pulled the plug and ... fans start running, A/C blows ice cold for good.
It's the rearward plug, the smaller one.

Now all I need is a new switch and an idea how to change it. Does it sit on a Schrader valve as the others do?

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[secondchance]

Yes. High pressure switch screws onto Schrade valve. However, at least in my case, Schrader valve is in stuck open position. Also, high pressure switch is tough to find for later cars 93 to 95.
I didn?t want to pay $400 for refrigerant evacuation and refill to replace the valve. So, I spliced in a toggle switch so that I can manually turn on the fan (in traffic) when engine temp is too low to turn on the fan. And turn off the fan at highway speed since speed will keep the air flow across the condenser.
Fans are dependent on engine temp and refrigerant pressure to turn on. For primary and secondary fan strategy, refer to shop manual.
I think for 91, part number is acdelco15-2352.

Glad I could help!

[ram_g]

Originally Posted by Matt B

Yun, I don't know if it's appropriate to state it that clearly - but I think I love you [emoji1787]
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Lol, he is certainly special! He sent me, gratis, the coolant bleed L fitting that goes on the driver side of the manifold, when my car had an incorrect part installed. And his "Yun mod" for the foglamp relay to help with LED headlamp installations is absolutely spot on...

(So as not to be a threadjack - congratulations on getting your AC working again!)

[Matt B]

Thanks, very good hint! I didn't consider the electrical diagnosis manual but the information i need is right there!

I'll unplug it later today and check the condition.

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[Matt B]

Thanks again. I ordered a FourSeasons part to conclude testing. If successful I will search for a GM part.
Adding a toggle switch would be my second option, too. So the imaginary "Emergency Switch Board" becomes larger and larger... Emergency switch that grounds Fuel Pump 2, "Economy" switch that cuts off low pressure cycling switch to stop the compressor, toggle switch for the secondary fan... They all might come in handy at a point

[Matt B]

Swapped out that switch today. A/C blows ice cold now!! As usual amazing help here.
Took her right out for a spin to a local beer garden to celebrate with some fine Bavarian beer!

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[Matt B]

LOL - not taking it as threatjack! Good to see that someone shares my appreciation!

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[secondchance]

Least I can do guys. I got a lot of help from other Z guys.
Matt - I?m happy to hear your AC is back.