I've noticed that my car has constant heat blowing through the defrost vents, near the windshield. I read that it could be a vaccum leak. I need some help with this since I dont know where to start. I went to look at my car and simply dont know which hose it could be. Thanks.

 

A common leak is at the switch itself. Turn the system on and stick an ear to the control unit. If you hear hissing, you've found your culprit.

JamesC

 

okay, but here's the kicker. I have a berlinetta, and the controls are purely electronic, except for the temp lever, thats gotta be a cable. Should I check that part out, or should I take it apart.

 

There is a wiring harness running through a body grommet somewhere under the blower/A/C case that has 2 vacuum lines and the blower wiring coming out of. One of the lines may be running to a coolant control valve, which is the output to the valve. The other is the system input, which may have gotten melted, pinched, or broken during a recent repair. Check that first before you go hunting into the electronic controls, which may need to be replaced altogether if there is something wrong with it ($$$).

 

There should only be 1 vacuum line running from the heater harness to intake manifold vacuum. ( the coolant diverter was added to later years. ). First thing you need to do is to check to be sure this line is connected. If OK,.... then close the hood.

That vacuum line will connect to a rubber vacuum line inside the car. Remove the passenger side lower hush panel and look for this connection ( I think it's a purple rubber line ). It should be very close to the center console near the firewall. This is the vacuum IN to the Berlinettas Vacuum Control soleniod. Be sure it's connected correctly.

If those vacuum IN connections are OK then you can assume the problem is occuring @ the Soleniod ( Dead unit ), at the heater pod ( broken contacts or computer failed), or inside the blower case. ( obstruction ). At that point your option is to replace the defective part &/or remove the dash housing to access the case.

If all else fails and you need a replacement solenoid - I've got a Vacuum Control Soleniod I can sell,..... but I can't test it. ( I don't think I have a working pod - but I might ! ) The Solenoid is too deep behind the dash for me to pull mine out just to test this spare unit ! I can verify that the pod sends the proper "MODE" voltages to the soleniod,....... but I don't have vacuum on my testing station so I can't verify the solenoids out-put.

 

P.S. Temp rheostat controls an electric motor. ( no cables )