JG928S4

Hot Water Valve Functioning correctly? Actuator ? 88 928 S4 Auto

When I start the car the valve Goes from the normally open to a closed tight (arm pulls all the way in), setting on air temp at low. When I turn the AC on, the valve flutters around, does not stay all the way closed, but does not open all the way. I did find the vacuum line (white) rubber connection kind of crumbling and replaced, but the valve lever still seems to not stay all the way shut. Diagnosis? Hoping this is the next step to get the AC flowing colder.

I did read about wiring it fully closed for the season, but hoping to check and see if there is a easy solution before taking that step.

the flyin' scotsman

I wired and glued mine closed for the season.

The only other solution is to replace the valve and thoroughly go through the HVAC system.

PorKen

I turned the pot CCW to release it from the valve, and left it hanging at full closed, with the vacuum line still attached. My A/C is chilly cold, now.

JG928S4

I turned the pot CCW?

StratfordShark

It sounds like when you engage the aircon, you're opening a solenoid to switch vacuum to another actuator on the HVAC system and that actuator has a leak somewhere.

To find it you have to check all the vac pipes coming from HVAC manifold.

If there is a leak then it would pull down the vacuum to the hot water valve, which would be periodically 'topped up' from the brake booster as the car idled but wouldn't hold. My guess is that this is why you see the fluttering behaviour and failure to hold full strength vacuum on the hot water line.

The WSM manual has a good diagram of the system which makes a lot of sense once you've whiled away time checking the vac leads. Maybe more helpful is the table showing which actuators are engaged and at what position when you select HVAC options including A/C.

dr bob

Most Likely Suspect is the recoirc flap actuator. It closes when the AC is activated and outside temp is higher than target temp set at the slider. As a temp fix (sorry...) you can wire or tie-wrap the heater valve in the closed position. You'll want to get the recirc flap fixed though. It needs to be closed to get max cooling in a hot car.

I recommend that you consider replacing all of the actuators at the same time, ezpecially if you are going to have to pull the console or the pod. They are probably the same age, and one failed means the others are close behind.

JG928S4

Thank you for the input

I wired the heater valve closed, and the AC does work better, I will put the actuators on the list of things to do at the end of the Summer.

Once I pull the console and Pod I might as well do the leather Pod, dash, new stereo, replace dash bulbs, ........etc. etc. etc.