Heater water flow problem?
10-29-2001, 10:52 PM
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Heater water flow problem?
Heater quit working some months ago about the same time as vacuum lines melted thru. Replaced vacuum lines. Saw the nylon arm on the heater valve was broken and just replaced with new valve. Odd, but no coolant poured out during valve replacement (?).
Checked vacuum but does not appear vaccum coming from blue plastic line from firewall. Ran direct vacuum from manifold to valve so it is now opening. Still no heat in cabin. Tried to bleed coolant system by using the bleeder screw near cylinder #1.
Engine temp running ok.
So the question is....any idea why no heat in cabin? - Mark
Checked vacuum but does not appear vaccum coming from blue plastic line from firewall. Ran direct vacuum from manifold to valve so it is now opening. Still no heat in cabin. Tried to bleed coolant system by using the bleeder screw near cylinder #1.
Engine temp running ok.
So the question is....any idea why no heat in cabin? - Mark
10-29-2001, 11:38 PM
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No fluid leaked when you replaced the heater control valve??? That sounds bad like a complete clog or somthing. When was the last time the coolant was flushed and was the heater valve in the open position when this was done? I don't know...this sounds strange... 
10-30-2001, 06:32 AM
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You need to have vacuum to the rest of the heater components otherwise all the flaps will be closed and you will not get any warm air, there shoudl have been some coolant at the valve but not much will leak unless you remove the expansion tank cap.
Note also do not test this with the car at idle, the water pump is not running fast enough to circulate through the heater matrix, take the car for a drive then stop and check if the heater pipes are warm.
Martin http://members.rennlist.com/martintaylor/
Note also do not test this with the car at idle, the water pump is not running fast enough to circulate through the heater matrix, take the car for a drive then stop and check if the heater pipes are warm.
Martin http://members.rennlist.com/martintaylor/
10-30-2001, 03:46 PM
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thanks for the feedback. When I have live vacuum attached to the (red) tube going thru the firewall it seems there should be vacuum coming back out the return (blue) tube to the heater control valve? Obviously the in cabin heater temp **** has to be turned full right.
Am I wrong with this assumption?
Since it appears there might be a problem under the dask with the Temp ****, I did a vacuume bypass directly to the heater control valve. I can see the valve open but cannot tell if hot water is passing into the cabin. It is does not feel like any warmth in the cabin when I feel around the hardware. I'm still assuming there is some sort of air block (?) preventing coolant to heater core.
It would be helpful if someone could explain how the in-cabing temp control **** operates. Does turning the temp up operate a vacuum change as well as other flaps, etc.? I thought the flaps were controlled via electric motor.
All feedback appreciated....geting cold here!
Am I wrong with this assumption?
Since it appears there might be a problem under the dask with the Temp ****, I did a vacuume bypass directly to the heater control valve. I can see the valve open but cannot tell if hot water is passing into the cabin. It is does not feel like any warmth in the cabin when I feel around the hardware. I'm still assuming there is some sort of air block (?) preventing coolant to heater core.
It would be helpful if someone could explain how the in-cabing temp control **** operates. Does turning the temp up operate a vacuum change as well as other flaps, etc.? I thought the flaps were controlled via electric motor.
All feedback appreciated....geting cold here!
10-30-2001, 04:11 PM
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I'm assuming that this is on a post '85.5 car, but, really, this ain't the Psychic Porsche Line... 
The heater control brain compares your setting on the **** to three RTD temp sensors. It activates a solenoid vacuum-control valve to open the heater valve if more heat is needed. IIRC, one air flap is vacuum-operated by the other solenoid valve, and the other flaps are servo motor operated.
Once you sort out which solenoid vacuum valve is which (passenger's side of center dash, up under on the side of heater unit) and which line is the one going to the heater valve, you should be able to get hot water to the heater core by applying vacuum, I think.
Dunno what kind of distribution of hot air you'll actually get, if the brain is f'd up, tho'. And this whole problem may be keeping you from getting a good air-out bleed on your cooling system (heater valve needs to be open), so you may have an air-lock in the core.
HTH, & good luck. These systems can be a bear once they get out of whack. You may want to check the archives here for more info.
Jim, time to go to "work"....
The heater control brain compares your setting on the **** to three RTD temp sensors. It activates a solenoid vacuum-control valve to open the heater valve if more heat is needed. IIRC, one air flap is vacuum-operated by the other solenoid valve, and the other flaps are servo motor operated.
Once you sort out which solenoid vacuum valve is which (passenger's side of center dash, up under on the side of heater unit) and which line is the one going to the heater valve, you should be able to get hot water to the heater core by applying vacuum, I think.
Dunno what kind of distribution of hot air you'll actually get, if the brain is f'd up, tho'. And this whole problem may be keeping you from getting a good air-out bleed on your cooling system (heater valve needs to be open), so you may have an air-lock in the core.
HTH, & good luck. These systems can be a bear once they get out of whack. You may want to check the archives here for more info.
Jim, time to go to "work"....