Discard the valve all together and plug the vacuum line as if there was no bypass valve
Low coolant? Bad thermostat? Heater core plugged, restricted, or airbound? ============================================================== Good answers by original poster. I would recommend replacing the t-stat first. Its pretty straightforward. If that doesnt solve your problem, our 89 acclaim's have a heater valve (it shuts off coolant flow to the heater core when the a/c is activated to increase the efficiency of the a/c) by the firewall that can stick or lose vacuum (broken vacuum line). Check that next. Lastly, I would take the lines off the heater core and run a garden hose up to it. This will "backflush" any accumulated crud out of the heater core. I do this to my Acclaim every fall and cant believe the crap that comes out! ============================================================== When the heater went out in my car, I went in and found out that it was the heater control valve. Check it out.
You can find a manual at oriellys called Chilton Chrysler front wheel drive cars 4-cyl !981-95 repair manual
There is no heater control valve on this generation of dodges like there used to be... the water flows constantly through the heater valve.. the only control is a trap door that allows cab air to be run through the heater core and is controlled by a vacuum solenoid in the heater box.. the temp control is also vacuum operated but be sure to check the vacuum supply line coming in from the engine.... it has a check valve in it that can be keeping the controls from getting enough vacuum to operate properly.. if you don't have a mighty vac just get one of those packs of barbed vacuum fittings from your local shucks and bypass the valve temporarily and see if you get heat... hope this helps
evap vacuum cut valve bypass valve
It is not adjustable. It is computer controlled. If idle speed is incorrect you have a vacuum leak or a sensor/solenoid issue.It is not adjustable. It is computer controlled. If idle speed is incorrect you have a vacuum leak or a sensor/solenoid issue.
The heater/ac doors are all electric. They are not vacuum controlled.
can happen when vacuum line is disconnected . look under hood to right of heater hoses. one vacuum line goes to heater valve (gate)on heater hose ,the other should go past this to a small sized metal object the size of a small lemon. if this is disconnected only defrost will work. I HOPE YOUR 91 IS SIMILAR TO MY 93.
You can find a vacuum line diagram for a 1993 Plymouth Voyager in the owner's manual. You can also find it at various auto stores.
If it's "broken" then you have no breaks. More likely its leaking (internally or externally) and your breaks are soft, or need to be pumped. If it's just hard to break, check the power boost (a vacuum assist on most cars).
I am not sure what you mean by the radiator bypass. But it sounds like you have a loss of vacuum to your AC/heater control. When you have no vacuum to the control, it defaults to defrost. There is only one vacuum supply entering the passenger compartment through a black hose under the hood on the passengers side close to the AC lines where they go through the dash. There is also a vacuum canister right there. See if you have knocked a vacuum hose off right there.
The heater blend door is not run by vacuum. It is run by an electric actuator.
if im not mistaken the heater control has vacuum lines. take off heater controls and see if you have a bad vacuum line to heater box.