1966 Ford Mustang - HVAC

To honest it is a 1966 Ford Mustang
classic convertible. 302 v/8 a/c, auto transmission. Beautiful. The engine is new as is the radiator and $1,000 plus parts to remedy the fact that on a warm day in SoCal were we live if I try to go up any mountain the new heat gage and sending unit registers HOT. We like the a/c. Is the only other remedy to remove the evaporator which blocks air flow to the radiator? We did remove the evaporator with the help of a a/c mech. and the overheating pretty much went away… Can the evaporator be relocated? Vendors?

Long time fan now reading at the Antelope Valley Press in Palmdale, CA Thanks

Do you have a fan shroud and a high-performance fan?

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The thing in front of the radiator is the condenser.

The condenser can’t be relocated. It needs high air flow for it to condense the refrigerant.


Did you get a high-capacity radiator?

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I have a 4WD Ford truck similar era and similarly configured, 302/C4. No AC though. I’ve had overheating problems during 4WD rock crawling at slow speed, but never highway driving, going uphill or not. I don’t think AC is the problem, although it may contribute to the symptom, but the problem is something else. Suggest to have your shop check these

  • ignition timing, both at idle, and the advance curve w/rpm and the vacuum advance
  • is the fuel mixture too lean? (carb problem, vacuum leaks)
  • is cooling system holding pressure?
  • is the water pumping at the correct flow rate?
  • thermostat in good shape?
  • is there a head gasket leak?

Folks with my same 4WD rock crawling overheating problem – common complaint on 4WD 302 trucks of the era – usually solve it by replacing the radiator fan with an electric fan and an improved performance radiator. .

BTW, one of the best Classic-Ford mechanics in the country is in the LA area, Mark Sanchez, Advanced Engineering West. He could solve it for you.

What I would do is install a thermal limit switch to the compressor clutch. Most modern cars have this feature.

So as you start to go up a mountain and the engine starts to overheat, the thermal limit switch opens, cutting power to the compressor clutch.

Now you can climb the mountain without overheating, and as you come off the mountain and the engine cools down, the thermal limit switch closes, and the compressor starts working again, providing AC.


Is the correct fan on the engine? There is a great deal of difference in the fans depending on AC.


The 4 blade likely wouldn’t be enough to handle AC and a long steep hill.

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