No Heat

[84EspritS3]

Hey guys, I've got a '95 S4. There's no heat. The switches work, the fan comes on, and the cables operate the vents, etc.., but no matter where I set the settings, I can't get any heat. Any ideas?
Thanks

[s2mikey]

Im assuming the car is warmed good when you try this. Maybe the thermostat is sticking? I remember from the old days of working in parts stores that bad thermostats caused many an issue in winter for people with no defrost and heat.

Is everythinjg else with the cooling system working right? Running temp good and all that? If thats all good then its possible that the slider/switch is bad or not engaging something it should. Just a guess.

[sailorbob]

The most likely culprit is one or more of the vacuum lines has come adrift or a union has split. If the vacuum pump is running constantly then this is an indication of this. Pull the vacuum line off the pump and plug the inlet with your finger, if the pump stops then it's OK. You'll then have the fun of tracing the vacuum lines to see where the leak is - not much fun if you get as far as those parts in the dash!

[QuadCam]

check the coolant system ,too.

Alot of times if you don't have a full coolant system, you won't get any heat. Could be a big air pocket in the heater core...... I've seen that in other vehicles. Not sure if that's an issue on the Esprit though.

[84EspritS3]

Thanks. I'll check these things. The coolant system works fine. Coolant level is where it needs to be. I know I have to wait for it to come up to temp. All controls work as they should. Thermostat works fine. May be the vacuum pump.

[jtrealty]

Check the two small hoses going to and from the heater core. Feel if they are getting hot. If they are it is a duct problem. If they are not it is a coolant problem. Make sure the coolant system is full. It is possible the heater core is plugged up or the heater valve is stuck.
David Teitelbaum

[judgea]

When putting in my built-in radar detector, I nudged the vacuum lines TWICE disconnecting them under the dash. Check that (unfortunately, I only remember the line connected somewhere under the passenger dash, sorry can't be more help, but someone may be able to post pics. I do remember it was more of a feel process, b/c you really can't see anything.)

Did you remember to close the vents? You have to do that to feel the heat pumped in. The heat will only come in above the dash (the slender, upper dash vents that don't close or open) and under the dash in the open piping which is just ty-wrapped with nylon under your dash.

[lotus4s]

As Mark said, heated air only comes out of the windshield vents and the footwell vents. You must close the dash vents or they will continue to blow cold air.

Then you need to have the knobs positioned correctly.
The right knob should be in about 11-12 o’clock position to get heat from the foot well vents, the left knob should be almost full counterclockwise, the smaller a/c knob should be full counterclockwise (compressor off).
As you turn the right knob further counterclockwise, it should start flowing heated air from the windshield vents along with the footwell. Full counterclockwise should be just windshield vents.

If the air distribution changes from windshield to footwell then you know the flaps are working correctly. If still no heat, it could be the cable actuator to the diverter valve for coolant to the heater core has come loose (the left knob). You'll need to pull the center console, radio and take the dash apart to locate/fix that problem.

If all that is working correctly, the heater core may be plugged with crud. You would then need to backflush the heater core to get it cleared and working again.

Good luck and be sure to update us on what you find.

[englishcarguy]

Thanks guys, I just had the intake manifold off for an oil sender replacement and CC pump rebuild and couldn't get heat out of the dash (face) level vents. It never dawned on me that it's not supposed to come out of there. Another weird Brit car thing.

[lotus4s]

Yes, it is pretty goofy...