Climate Control

A/C Blows Cool Air, but not Cold

>Compressor works, freon still in there (no bubbles in sight glass), blows cool but not cold,
>I guess this is common with these but I bet I can do SOMEthing about it...

I know what you mean. Mine was the same way, but now it's nice and chilly. While I had things torn apart in the engine compartment last week I went ahead and replaced the heater bypass valve. This is a vacuum-operated valve that blocks the flow of hot water through the climate control when not needed. Mine held vacuum just fine, but I replaced it anyway. What a difference! Not only is the A/C colder, but I can now run the car in the evening with the A/C off, vent on, and not have warm air coming out from the console vents. Call Dave Roberts to get one.

Replacement Procedure:
1. Remove air filter. Remove lower air filter housing
2. Locate heater bypass valve - right (passenger) side of engine compartment, between engine and firewall.
3. Loosen hose clamps and slide them out of the way. Remove vacuum hose from valve actuator
4. Place newspapers and catch pan under vehicle and/or position a rag underneath the valve
5. Remove old valve. Less than one cup of coolant will leak out.
6. Insert new valve and reinstall hose clamps and vacuum hose
7. Bring engine up to operating temperature and check for leaks. Any spilled coolant will be evaporated by engine heat.
8. Replace air cleaner, and go and enjoy a cool ride on a hot day!

Tip: Twist hoses to loosen, then carefully use a flat blade screwdriver to help slide them off.

+Greg Nichols
'87S4


A while back I asked which direction the coolant flowed through the heater valve. Didn't get an answer so checked it myself. Easy but a bit messy. For those that care, it flows from the engine through the valve then to the heater. The valve is directional. The one I replaced was in backwards so it pays to double check. The dud valve also gave every appearance, externally, of working correctly but the internals were toast. Made a BIG difference.

Colin Plastow