Technical Heater can work, but mainly blows COLD air

[genehugger]

I have searched this forum and read quite a bit about the heater matrix (and how to change it) as well as lots of issues related to the temperature control, but my searches of this forum did not uncover anything that sounds exactly like my problem.

Basically, at some point this winter I noticed that the heater does not work. The car would just blow really cold air, almost as if it was colder than the air outside. I now have the theory that if I rev the engine immediately after starting the car, the heater will work, albeit not indefinitely. When functioning, the heater gives a good airflow of nice warm/hot air. But eventually, the air starts to get cool again and then will just be so cold that if I do not shut the valve (0-max) I freeze in my car.

So the question is, can the heater matrix or the temperature control valve on the side of the heater unit be at issue here when the heater can work sometimes?

The panda is a 1994 non-4x4 1000 and I replaced the radiator at then end of summer and there are no coolant leaks of any kind.

Hopefully, someone here can help me identify what is wrong with my sweet.

 

[lightweightmick]

Hi,
I had similar to this and eventually found it to be the water pump at fault. The plastic vanes (if indeed you have one with plastic impellar) expand at a different rate to the shaft and to begin with you might not suspect the pump - as it gets worse you would begin to get problems with overheating - intermittent initially. The pump at times lacks umph to fully circulate the coolant - the heater being the highest point to circulate it to, of course.
If you are sure you don't have an air lock and that the valve is open (remove battery and insulation to check this) I would advise that you check your water pump - if you find it has a plastic impellar discard it and fit alu impellar type.
If you do this when the engine is cold you may think there's nothing wrong with it!
I took mine out while the engine was still hot (though not at operating temp) and guess what? I could just turn the impellar on it's shaft while gripping the toothed drive pulley.
This took some sorting as it only occurred when the engine warmed up - was fine when running cool - though the heater behaved as you describe. It blows warm for a while due to thermosyphon, but soon loses its heat as the coolant isn't circulating as it should.
Worth checking, and it's at the top of my list in future!
hope this helps,
cheers
lwm

 

[genehugger]

Exactly the kind of non-heater solution I was hoping to find out about. I will check this out and post back. It is about to start snowing here but as soon as I can fathom going outside again, I will take a look at the water pump.

Thank you so much, this forum saves my panda every time...

 

[genehugger]

Hi,
I had similar to this and eventually found it to be the water pump at fault.

Ok I have now read my Haynes manual on the coolant pump and they state the pump should just be outright replaced as a unit. I will go to the parts store tomorrow and see what they can get but figured I would post here first in case this idea prompts some warnings or advice from any members.

I will admit, I am not really into working on my panda when it comes to things like draining the coolant, so if I were to go this pump route, it would be to buy the replacement, then drain, replace and refill. Sort of wonder if I should not just replace the matrix while I am at it. All of these parts are original (except the radiator).

Thanks

 

[VmanC]

It sounds to me like the problem is as LWM says, water pump or airlock. It's a small job to have to drain the water again if the pump doesn't cure the problem, and you can always catch the coolant in a container to use again, save wasting antifreeze, so if it was me I'd leave the matrix for now.
When you do refill, make sure you have the bleed screws open, one at the top of the radiator and one in the heater hose just behind the carburettor/injection unit, you'll always get an airlock if you don't.

Good luck with it.

 

[toonstar1977]

I had a similar problem and i changed the water pump and it made no differance.
The problem turned out to be a sticking termostat.

 

[genehugger]

I had a similar problem and i changed the water pump and it made no differance.
The problem turned out to be a sticking termostat.

Can you clarify? Was it the thermostat on the radiator, the radiator thermostatic switch? I assume that that would be a rather easy part to replace.

Thanks to all.

 

[VmanC]

Can you clarify? Was it the thermostat on the radiator, the radiator thermostatic switch? I assume that that would be a rather easy part to replace.

Thanks to all.

I'm sure toonstar is talking about the engine thermostat, it's located directly under the distributor at the gearbox end of the head. It's built into the housing that the top radiator hose attaches to.
You replace the whole housing to change it, very easy job, it's only held on with two bolts.

 

[lightweightmick]

Thermostat sticking open will result in cool running and temp gauge reading low, but heater would blow warmish air. Gh is describing 'really cold air'...

 

[Harllequin]

I'd check the temp of the water going to the matrix.

Run the car at its normal operating temperature, have the heater control set to its hottest position.

Now go into the engine bay, there will be 2 pipes going into the bulkhead. One will be the flow of water too the matrix, the other will be the flow from the matrix.

Carefully take hold of each pipe, one should be very hot, the other quite hot.
If they are not there is no hot water going to the heater.
If one is very hot and the other quite cool there could be a blockage in the matrix.

Hope that helps you a bit.

Once you know what temp the pipes are post back and we can see what the next best step would be.

 

[toonstar1977]

Can you clarify? Was it the thermostat on the radiator, the radiator thermostatic switch? I assume that that would be a rather easy part to replace.

Thanks to all.

HI it is the termostat on the engine and it is very easy to change.But this may seem a stupid question but is the anti-freeze topped up? not having enough coolant would course a similiar problem

good luck

 

[genehugger]

Ok guys and gals. The heater works. But, I did not actually try to fix it. We have been under snow and rain and cold, and thus I never got motivated to really work on the car. Then last weekend, I found my battery died. While changing the battery, I did top off the coolant, but added only around 12 oz, there was coolant visible in the overflow, so I really did not add much.

So before I say this is solved, does any one have an idea why a dying battery would cause the problem, or could it be that missing 12 oz of coolant?

I swear the day after the new battery, it got cold again, but monday and tuesday, morning and evening commutes, nice hot heater, for 1 to 1.5 hours at a time.

 

[VmanC]

Ok guys and gals. The heater works. But, I did not actually try to fix it. We have been under snow and rain and cold, and thus I never got motivated to really work on the car. Then last weekend, I found my battery died. While changing the battery, I did top off the coolant, but added only around 12 oz, there was coolant visible in the overflow, so I really did not add much.

So before I say this is solved, does any one have an idea why a dying battery would cause the problem, or could it be that missing 12 oz of coolant?

I swear the day after the new battery, it got cold again, but monday and tuesday, morning and evening commutes, nice hot heater, for 1 to 1.5 hours at a time.

I'm sure your heater problem and the dead battery are separate problems, the battery would not have any effect on your cooling/heating system.

I wouldn't draw a line under this problem just yet, topping up the water could have made a temporary fix only. I'd check your water level regularly for the next couple of weeks to see if it goes down again, if it does you may have a head gasket problem.

But lets be positive about it and hope that all is now good.