68 SS 396 El Camino Air Problem

RHinkel764 · Posted: Sun Jun 29, 2008 10:44 pm Post subject: 68 SS 396 El Camino Air Problem

Hey El Camino Compadres:

I have a 68 ss 396 with original a/c. I have restored the car and the a/c system- everything is new-compressor, condenser, evaporator, dryer, expansion valve, hoses and virgin r-12. The only used thing was a POA valve I bough from ebay that was"cleaned and tested".

I had the system evacuated and filled yesterday and the good news was no leaks, the bad news , I seem to have an air mixing problem with the a/c and heat. The a/c guy was very reputable and said it looked like the system was working on the outside of the car as it should- evaporator was very cold and sweating but the air in the car was only 60 degrees at the vent and warmed as the car warmed up. The whole unit was rebuilt and new seals put throughout the unit-any ideas from anyone that might have experienced a similar hot air leak? All cables are working and they seem to be adjusted. I want to avoid taking the whole inside portion of the unit out if possible. Anything I might have overlooked? Thanks Rob

CANTED · Posted: Mon Jun 30, 2008 9:06 pm Post subject: heat on

Could be that the heat control valve is not closing fully. A quick check would be to pinch the heater hose near the valve with some type of clamp and see if it changes your duct temp.
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RHinkel764 · Posted: Tue Jul 01, 2008 11:25 pm Post subject:

I will try the cut off this weekend coming but I'm a little bummed to have spent so much care in rebuilding the evaporator unit and to have it not work properly (so I tend to believe). Inside the car, where the heater core sits behind the fiberglass walls of the unit, it gets very hot to the touch, too hot to even hold my hand on for long when the car is at full temp. The car temp shows very cool but this area is HOT inside the car.

464elky · Posted: Wed Jul 02, 2008 6:14 am Post subject:

definetly sounds like the heater control valve is letting the coolant though. Be aware that there are two types of valves that look just alike. One opens when vacuum is applied and the other opens when vacuum is absent. Make sure you got the right one.
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Another 3 to 9 years should finish it.

skinyfisher · Posted: Wed Jul 02, 2008 1:30 pm Post subject:

464 Elky is right as always. Have been there and if your that hot your valve is not working and is stuck. They do corroid inside the valve if the unit has not been used or your systems is dirty. With all you have spent and done this is the easy part and the cheapest replace the valve. Also check your vac line to the valve from vac tank and cntrols.

464 I thought you had the 2-100 A/C unit in your race car.
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RHinkel764 · Posted: Thu Jul 03, 2008 9:18 am Post subject:

On the 68 model, is there a heater control valve that lets coolant through? The only vacuum I have is for actuating the vent doors. Is the valve located inside the evaporator unit? I know on later years, the valve is located on the passenger side fender well. Your input is appreciated

Rob

RHinkel764 · Posted: Thu Jul 03, 2008 8:45 pm Post subject:

Ok- I got home a little early for the 4th celebration and went through all my manuals and exploded views. I took out the glove box and disconnected the heat/cold cable on the unit and put it in a position where I could hear the door slam on the heat opening. Started the car and put the a/c on. With an outside temp of 85 deg, the car warmed up and I put the old meat thermometer at the vent. Sitting still at 1500 rpm, warmed up, the center vent read 52 degrees. I think I have a working system. Thanks all for the input- the road test will happen tomorrow- I'll see if anything goes.

Just for the record, the 68 model has no heater valve, the coolant alwa Happy

ys runs through the system. Since originality is an issue for me, I may not put one in but I am very tempted to tastefully install one for even better performance.

Thanks

Rob

RHinkel764 · Posted: Sun Jul 06, 2008 9:47 am Post subject:

I've decided to put in a diverter valve. I am using the 69's version. I was wondering if anyone knows which hose I divert? The one from the water pump or from the intake? The hose size looks to be the one from the intake but want to make sure before I do the cutting.

I have too much heat in the passenger compartment from the heater core coming through the unit. A/C is cool but the heat emitting from the core is offsetting and uncomfortable on the feet and passenger.

Thanks

Rob

464elky · Posted: Sun Jul 06, 2008 1:00 pm Post subject:

Rob, I just installed a vintage air system in a 67 vette and the diverter went in the hose from the intake. don't know if yours is routed the same but I thought it might help.
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Another 3 to 9 years should finish it.

RHinkel764 · Posted: Sun Jul 06, 2008 4:55 pm Post subject:

Thanks That was my guess. With odds at 50/50 I should hit Vegas.

Good luck with the Vette

Rob