Fans & baffles work, water hoses to firewall warm but no hot air comes out of any vents.
How would I start to search the problem.
Thanks for any and all suggestions.
What year of car? Adding that and your location to your J-l profile provide important info for the troubleshooting process.
It’s a 1994 xj40 vin #698893. Sorry I neglected to include that in the post. Bad me!
You have a 1994, so you should have a vacuum-operated water valve screwed into the back of the head:
The purpose of this valve is to prevent the flow of hot water through the heater core when air conditioning is employed. Normally these valves will fail in the open position (allowing water to flow when heat is not needed) but should the valve fail in the closed position you will get no flow of hot water through the heater core.
So are both heater hoses hot, or one hot and the other warm but not as hot? Or is one cool relative to the other?
When the same thing happened to my 94 Sovereign it was because the main coolant thermostat had stuck wide open. The heater hoses that enter the bulkhead felt ‘warm’ to touch but not exactly hot. The pointer on the dash gauge barely moved out of the cold sector when travelling over 30 MPH but would rise a little in heavy traffic but not to the usual ‘N’ position. Once I’d changed the thermostat it all went back to normal. I hope it is a similar easy fix for you.
Both hoses were equally warm but not hot, and I am now thinking that the heat I feel might be from the hoses proximity to the hot engine.
I should mention the a/c is not working due to damaged condenser but that’s an issue for another time.
I have never had an over heating problem in the 10 years I owned it. Engine heats up normally and always maintanes temp on the norman mark.
Gary, did you get the ‘no heat’ situation sorted?
Hi Mike
No I have not had further oportunity to work on it do to other issues. I did check the demperature difference between the two hoses in and out of the central heater box, one was warm and the other to hot to hold more than a few seconds.
I should be able to chech that out later next week. Thanks for keeping in touch.
My guess is the upper blend door is jammed by a broken demist flap.