When I checked out the car before purchase I of course checked the AC (which blows cold) and all the different vents and they all worked fine. It was almost 90 out so I didn't check the heat.

Anyway, the one thing I didn't check is not working.

Yes I looked at some other threads but I wanted to see if you all can answer some specific questions.

I get nothing but cold air from the heat. It doesn't even blow a little warmer so I'm guessing either a stuck or locked heater valve or a bad pump. The manual warns against testing things with a multi meter but I'm guessing checking to see if the valve and the motor are both getting juice is a good place to start. Yes? No? maybe?

I was planning on swapping out the coolant anyway so maybe a flush is in order. Is there a way to flush the heater core without dismantling the interior of the car? Anything I should or shouldn't do when executing a flush?

Anything else I should be looking at as the cause for the lack of heat?

Thanks

Eric

 

Before assuming the worst that either the pump or the valve has failed, a sharp tap on the valve with the wooden handle of a hammer can often encourage a stuck one back to life.

It could well turn out be a failure of either part but I always like to eliminate the zero cost options first.

Cycling the A/C from max Cold to max Hot about once a month is good preventative maintenance to keep pump, valve and flaps working.

The cooling system is 'low volume / rapid circulation'. The small volume remaining in the heater core is of little consequence when you do a drain and flush. An intermediate fill and run with plain water followed by a flush and refill with coolant/water mix virtually clears any residual.

Graham

 

I'd echo the above and would also try to put the temperature setting at max (not just a higher temp) and see if it works then. The interior temperature sensor on mine was a bit dirty thus did not work well, but the max heat setting seems to ignore the temperature and just pushes max heat out the vents. If that works, then you need to clean the interior temperature sensor (small grille, just to the left of the steering column). If max heat works, but cleaning does not help, there also is a possibility that the fan that pushes air over the temperature sensor isn't working right. I've not had to change that, but I know there are threads out there about it.

 

Could be simply a bad thermostat. Does the coolant stay up to temperature when driving? (air flowing through radiator)

 

Ditto, on the thermostat

99.1% of a no heat situation is cause by a stuck open thermostat. It is a safety feature built into thermos when they go bad.

The only thing that heats up the heater core is hot Antifreeze/Coolant, the blower motor is a fan that circulate the air.

A stuck bypass valve, will cause a no heat issue, too. I meaning ME, use to check by pulling off the outlet hose (from the heater core), if no/little coolant flows, then most likely thats the problem.

The upper hose should be cooler (from the radiator to the engine) than the lower hose (from the engine to the radiator). You can use a laser thermometer to check, if both are the same temp given a 10 degree difference, will verify a stuck open thermo.

Running with a stuck open thermo, will not bring the engine to operating temps. Does your gas mileage change the hotter it is outside? You burn more gas when it colder?

 

POD184 - how do you remove the little grill to the left of the steering column to clean the temperature sensor?

thanks
Dave Christensen
65 Etype OTS
69 Etype OTS
03 XJR

 

Remove the spare change holder below the grill by removing the one screw. Then reach up and push out the grill,from the back.
Spray the sensor with some contact cleaner and blow out any dust.
Note: a failed or discomnected sensor will not produce a fault code, but an unplugged fan will.

Good luck

 

I didn't get to totally diagnose the issue yesterday but I don't think it has anything to do with the thermostat as the engine temp climbs to the midpoint and stays there.

I tried the all the way on hi setting and made no difference. Did the old up down up down on the buttons and that didn't help either.

How much does the water pump actually vibrate when operating? I touched it and there was slight vibration but the car was running so I'm not sure.
I guess the pump would operate if the car was switched on but the engine was not running so I will retry this.

I did the smack on both the pump and the valve selenoid but this had no effect.

I didn't disconnect any hoses as I am dreading the air bleeding process but I will today.

Is there any problem with hooking a multi meter up to the connections leading to the pump and the valve? If either had failed wouldn't they have thrown a code to the computer?

Thanks guys.

Eric

 

When I bought my car, I had no heat, and the Coagulated Coolant because the previous owner had mixed coolants. I could see it when I drained the fluid (chunky). I tried to drain and replace coolant, but my heat would not come out afterwords. It had plugged the heater core.

Now, I don't know if this is acceptable or not, but this is what I did:

I drained all the coolant. I placed a hose into the system and turned it on. I left the radiator drain open and started the car. The hose ran fast enough to keep the system filled while running, but just fast enough so I was not loosing a LOT of water.

I ran the car until it got hot, which took a while. It kept spitting out bad coolant/chunks for a long time. I kept running it and moving the heat controls until the Heater Core finally popped and cleared out the goop, and all of a sudden, I got heat! I drained ALL the water, and then filled with proper fluid.

A couple months later, my heater pump died, probably due to being overworked with a plugged heater core. I pulled the pump apart and replaced the brushes which worked for a while, but the stator was badly worn, so it only lasted for a couple months. I found a replacement at the junk yard for $15 and have had heat since. It's probably been a couple years now.

PS: The Temperature gauge is not a good way to determine if your thermostat is working properly. The gauge is more like an idiot light. It goes to middle and pretty much stays there, not showing accurate temp. Just an FYI.

 

I do believe this car has the recommended Jag coolant and always has so I don't think I'm clogged.

I imagine either the pump is dead or the valve is stuck or NFG.

What I would like to know is if I disconnect them to check and see if they work will I need to bleed the cooling system and if so how?

Thanks

Eric

 

So I checked the pump and the valve and the pump gets juice and if I hook it to a 13 volt source it spins. The valve gets juice but If I hook it to a 13 volt source it just clicks quietly. It's either blocked (but I doubt it) or frozen.

Has anyone had any luck fixing a heater valve?

Thanks

Eric

 

The most common issue is with the heater pump and lack of use.
A quick strip to check the brushes, regrease the bearing and an internal cleanup will usually bring it back to life. If you can get it out of the car and test it with a bucket of water and a couple of hoses attached?
I'd doubt the valve is to blame.

 

I hope this is all I need.

Thanks

Eric

 

I flushed out the heater core with and now I have heat. It's not piping hot but it will do on a chilly morning.

It had gritty sandy stuff in it


Thanks

Eric

 

Gritty sandy stuff!

Mixing early type coolant with the current OAT (Organic Acid Technology) coolants can result in strings of coagulated jelly in the coolant but NOT anything gritty or sandy.

The most likely source of anything solid like that is broken up plastic from the Water Pump impeller.

If the Water Pump is compromised, this would explain the lack of heat.

Graham

 

Gritty sandy stuff is not unheard of. Sediment can be expected depending on what settled out over time.

 

It seams to be calcium or sandy grit. Not plastic particles.

Thanks

Eric

 

Well maybe that's my problem! The heat in my jag doesn't work at all. When I turn it on it blows Cold air. So I'm gonna try some of the things mentioned in this thread and hopefully one of them works.

 

Connecting a garden hose to the outlet of the heater core and back flushing has been reported as being a good fix if the core is plugged.

 

It doesn't take much of a drop in the level of the coolant from a crack high in the reservoir to keep the auxiliary pump from picking up the coolant, leading to loss of heat.