plastex

I am having an odd issue on my 85.5.

I am getting no heat in the cabin. If I turn on the fan it blows cold air. Now I looked at the heat valve in the engine bay and found out that the PO had unplugged it for some reason.

My question is that I thought if the valve had no vaccum to it, it would remain in the open position and get too much heat into the cabin?

What/where/how do I start trouble shooting this. Winter is on the way here in Ohio.

Thanks,
Oscar

Calmchaos

The vacuum pulls the valve open allowing the hot coolant to flow through the heater core.
If it was disconnected from vacuum, that would be your problem.

Does the car get up to normal operating temperature?

plastex

It seems to get up to temperature fine.

Thanks,
Oscar

Rip It

Vacuum closes the valve. It's designed to fail in the open position. You may need to bleed your coolant system, with air in the system you won't get hot water flow thru the heater core.

75ohm

Bingo.

tifosiman

Well, let me add something else.

The heater control unit might be dead. I went thru this a long time ago. The valve was fine. The flap was fine. I couldn't get it to work until I replaced the control unit, then everything worked perfectly.

plastex

How can I bleed the system. I have heard to jack the front of the car and crack the bleeder open. Then fill it until it comes out. Everytime I read on how to do it is a little different. What is the best way to do it in my driveway?

Thanks,
Oscar

DarylJ

I don't know about the best way, but a quick way is to loosen the bleeder and jam a garden hose nozzle in the coolant tank. If you have a big nozzle covered in rubber you can make a good enough seal to push the air out of a basically full system with only a few ounces of water put in slowly.

I don't bother jacking up the front of the car.

krystar

or just open the bleeder up and idle the car until no more steam comes out.

DarylJ

Steam come out of your bleeder?

You're doing it wrong.

Calmchaos

I was wrong in saying vacuum opens the valve? Why does the vacuum activate when the heater is set to max then?
And if it's designed to fail open, then why does it failing cause the heater to stop working.

I guess I was wrong but that makes no sense to me.

plastex

Ok, bled the system and still no heat. The PO had rigged most of the vacuum lines and I am having to fix.

I notice that when the car was warmed up and I moved the heater selector in the car from cold to hot there seemed to be a slight change in the fan speed?,(or amt of air coming out of the vents. This makes me think that the control unit is working?

What do I check next?

tifosiman

I really think it is your heater control unit.

Rip It

If the PO had the vacuum hose disconnected, then the heater valve would be open regardless of the climate control unit. Maybe you should take a look at the water valve and note if the lever changes position when the heat is turned on and when turned off. If it doesn't change position then I would suspect a problem with the CCU, solenoid valves, or a faulty vacuum hose. Bleeding the system is a PITA, I get a loaner radiator pressuriser from auto zone, it works great, don't have to jack car up. etc...just attach it to the radiator coolant tank and bleed. "Search" threads is a great member feature, join ! Its also possible you have a clog in your heater core loop. Try to keep it simple.

plastex

I will try to do this while I am changing the Vacuum lines. My problem is that I had just figured that since the heater valve didn't have the vacuum hooked up to it there would have been heat in the cabin?