Heater is Haunted

[Steffan]

Last weekend me and the misses packed up for a trip to the Sholtz Car Show in Capac Mi. Well it wasn't very warm out so I fired up the bird and had it nice and toasty before we left home. As we headed out on the highway we lost all heat. The temp gauge was about mid way but all the heater did was blow cold air and there was a fair amount of cold air coming in near the passengers side floor vent (even thought it was closed)

Well today I checked the heater again. It warmed up the hoses were hot to the touch the heater was blowing hot air. I had the rad cap off and could tell when the thermostat opened and felt the upper rad hose and it was hot. Driving through the city I had heat.

Beats me what is going on.

Oh by the way I won 1st place for my division at the car show which was 1958-1998 Thunderbird. There was about 1800 cars of all makes at this show.

[DKheld]

WoW - congratulations on the win !!!! (surely you took pictures - hint hint)

Well thought for sure the heater control valve was operated by vacuum so my guess was..... At an idle - good vac - keeps the valve open. When headed down the road vac drops and valve closes???

Then I looked it up in the manual .....now ....I'm guessing maybe a bad control valve but don't see what a change in engine speed would do to effect the valve in the plenum. Could be something not shown like maybe the control valve in the plenum regulates the amount of vac applied to the actual heater valve that lets the water flow. They also mention cabling adjustment to the heater valve in the plenum.

Hope fully someone will have a better (less rambling) answer. Lucky for me I haven't ever had to mess with mine. I'm always wanting cool - not heat.

(or maybe it's just too close to Halloween ? )

Eric

TEMPERATURE CONTROL UNIT
The temperature of the heated air is controlled by a capillary tube operated thermostat valve that automatcally regulates the flow of water through the heater core. The capilary tube is located in the plenum chamber Fig. 18. The action of the
thermostat valve is regulated by the temperature control lever (top lever) in the heater control panel Fig. 19. The thermostat controls the flow of hot watcr from completely off to full on.

[simplyconnected]

Congratulations, Steffan. An award winning Squarebird deserves some PICUTURES!!! Your car must be beautiful and we'd love to see it. If you have any difficulty posting them, either Ray Clark or I can help.

Low coolant level or an air bubble will stop the heater. I don't know for sure if this is your problem but you may look into it. The pump pulls water from the bottom of your radiator and runs it through the engine. Engine speed will have an effect on coolant flow, too. Sometimes, when the water level is low, the heater core will produce a gurggling sound from air bubbles. When you check your coolant level, do it just as the thermostat opens, with the engine running at a good rpm, and above all don't burn yourself.

Capac is the area I hunt White Tail deer in. I have several friends who either own land or live there. God's country; wooded, green, plenty of streams, and farm land as well. Most of the farms around there grow carrots, sweet corn, sugar beets, etc. Soooo, with all that fine eatin', the Capac, Emmett, Yale, Brown City and Imlay City area (to all the way up 'the thumb') of Michigan is teeming with trophy White Tail Deer.

[Dakota Boy]

I dont trust any of those old vacuum systems on these cars.

When I got my heater/defrost working last Fall, I went with the cable-operated valve on the inlet. No vacuum needed.

[djberson]

Perhaps your coolant is low?

[bird 60]

Congratulations on your win Steffan. Love to see some pictures. Hope the Gremlins in your heating system have gone to sleep.

Chris....From OZ.