No heat!

[corvairdog]

Got a 4 cylinder 72 Vega GT a/c car with no heat. Ran it up to temp and no heat. Blower and all controls work fine. Seems to be warmer when moving it to warm than it is on cold but not blowing hot. What's the proper troubleshooting procedure for determining the cause? Thanks.

[bugdewde]

Plugged heater core.... or

The temperature control door may not be working. It's controlled by a bowden cable that's connected to the heater face in the dash to the heater assembly under the dash on the firewall.
Sometimes the cable breaks or the looped end of the cable comes off the temperature door actuator arm.

Look under the dash and follow the temp control cable from the heater face on the dash to the heater-A/C assembly under the dash on the firewall. When the control slider on the dash face is moved left-right, the cable should move in/out. If so, it should also move an actuator arm (on top???) coming out of the heater assembly box.
Not exactly sure of the location on an A/C car but it can't be too hard to find under there.

Here's the cable for a NON-A/C car..... but the idea is the same for an A/C car..... just gotta find it, to check it's operation.
SEE "TEMP DOOR CABLE"

scan0002.jpg

[corvairdog]

I continue to have no heat. It appears the car never reaches operating temperature so the thermostat never opens.

We tried putting both a 190 and 160f thermostats in the car. No change.
Replaced a bad water temperature sending unit. Car never gets hotter than 120f.

The fan is mechanically connected to the cam so the fan is always running. I had a 71 Vega back in 81-82 and never had an issue of no heat.

Does anyone have a clue on why this engine wont' come up to temperature? I've driven the car 20 minutes and let it idle for 45 min and the block never gets hot! I'm wondering if some space age nasa materials were used in this one to keep it cool? It had a lot of IECO mods back in the day to the block and head.

[beakerztoyz]

Does anyone have a clue on why this engine wont' come up to temperature? I've driven the car 20 minutes and let it idle for 45 min and the block never gets hot! I'm wondering if some space age nasa materials were used in this one to keep it cool? It had a lot of IECO mods back in the day to the block and head.

wow that seems like it should be hot after running that long.... I agree it must be space age nasa material !

[hammerdown7]

Since this car had several IECO mods, have you verified that water is flowing through heater core and also checked to see if the intake manifold water passage has not been blocked off? Since the water temp sensor is in the manifold the gauge may not be accurate.

Other than those two things, I can't think of anything else.

Dick

[corvairdog]

Well we removed the direct connected camshaft fan and installed a thermostat one. Engine now gets up to temperature and displays on the water temperature gauge. I get a little heat but not much. It should be hot. Heater core hoses appear hot (outlet slightly less so). I guess I'll need to flush the heater core.

Dick - can you tell me more about what the symptoms would be of a blocked intake manifold and how I can determine that?

[mastiff]

Just ran into something like that. no heat, that is. found the outside of the heater hoses looked and felt good. the inside was falling apart and plugging the flow.

[hammerdown7]

Well we removed the direct connected camshaft fan and installed a thermostat one. Engine now gets up to temperature and displays on the water temperature gauge. I get a little heat but not much. It should be hot. Heater core hoses appear hot (outlet slightly less so). I guess I'll need to flush the heater core.

Dick - can you tell me more about what the symptoms would be of a blocked intake manifold and how I can determine that?

The only reason I mentioned a blocked intake manifold is that I believe the water temp sensor is screwed into the manifold, that was just a guess. By the way that's the water pump the fan is mounted to.

Dick