Cheap air-conditioning

[OldGMJon]

Cool thread...I was wondering how I could make this "Harrison" under dash model that I took out of my 66'GMC 2503 fit my 65' Chevy panel. Can't live in SoCal without A/C.
Are your older systems still using R12 or have you switched them over to R34?

[chevyrestoguy]

Jon-
Where did you find that unit? That is a crazy mix of Chevy parts! Did GMC modify existing Chevy parts for their A/C equipped models or did a previous owner do some engineering to make it work in the GMC? The good news is, it'll work just fine in your '65. The evaporator housing that you show in your picture is nearly identical to the units used in the '64-'66 Chevy trucks. The ducts that you see attached to the sides are the exact ball ducts that Chevy used in the center dash A/C outlet. All you will need to do is buy a faceplate from CorvetteJim, cut the dash per the factory dimensions, and get the plenum that goes behind the faceplate that will also mount the three pull knobs. Of course, you'll have to fiberglass the holes shut in the housing, or if you're not a stickler for factory original, leave the ducts where they are and mount your pull knobs somewhere under the dash where you can reach them.

The older units can be converted to R-134 with no problems. I would suggest getting an evaporator that is designed for a R-134 system, changing out your dessicant/dehydrator, and putting in R-134 compatible O-rings throughout the system.

[OldGMJon]

It is a factory job I believe...the 66' GMC 2503 was originally from Long Beach, Ca. and came with factory power steering and power brake assist plus this A/C unit. The heater box has a separate flap to bypass the heater and allow fresh air into the cab. There is a template on one of these threads on how to cut this hole just above the heater air duct that opens to the flap in the heater box and has the mounting holes accommodated as you can see. It came with a Frigidaire compressor with factory GM mounting brackets. The dryer and condenser(that thing that looks like a cooling radiator) were mounted on the grille support in front of a large radiator. The engine is a 351E big block V6 so could handle the load. Those were the only two ducts as the ash tray is in the dash still. The unit also channels the defroster to the windshield. A rather compact unit that doesn't impede leg room as far as I could tell. I have a line on some R12 so that is why I asked...is the R34 the better route? jon

[OldGMJon]

Here are some shots of the heater box...has a separate cable pull for the middle flap. The tri-pull cable flange was mounted under the dash beneath the radio. jon