Hi bud

The resistor packs are a common fault but will not cause the lack of heat from the heater. check the condition of the water in the header tank to see if it has any exhaust particles or small amounts of oil in it. After you have ran the the engine for a short while check the bottom and top hoses off the rad. It may be something as straight foward as a thermostat. Fingers crossed it not the Head Gasket.

I am sure someone else could give you a bit more info

cheers

 

A faulty resistor pack would not cause the cold air issue you describe, the things to check for would be, air locks, first because they can cause much more serious problems if left.

The saab valve maybe stuck open meaning no hot water will pass through the heater matrix (if your car has one fitted, some do and some don't).

Thermostat possibly stuck open meaning that the engine will take a long time to warm up, especially in cold weather.

Also its worth twisting the heater control from cold to hot 4 or 5 times as the valve can become stuck if it is not used enough. I have this problem with mine and get no hot air until i have done this.

 

first i would bleed again the cooling system. just to be sure there is no airlock.

2.1) the heater valve can get stuck. there is a metal wire that pulls it forward.
this is the little culprit:
http://www.rimmerbros.co.uk/Item--i-JJB100240

2.2) on the other hand, there is also the possibility things are wrong with the dial. since it has the other side of the same metal wire.

3) SAAB valve is also kind of infamous.
http://www.rimmerbros.co.uk/Item--i-PCH003300
*however, air blown should be still warm.

if nothing good happens, it could be the heater matrix.

i imagine every Rover owner should detect a HG fail so, no point in saying anything about that.

good luck. i did the resistors, too. very easy.

 

ps2. thermostat has nothing to do with it. whether it is open or closed, heat should come out your vent ducts. and the weather outside really doesn't matter. just rev your engine harder for 5 minutes (4000-6000 rpm) and all your cooling fans will be on

 

I didn't really think the resistor pack could cause the second problem. I figured that I had two separate problems but wanted to get better opinions.

Ok, so I know how to check HGF - Cream in oil, oil in expansion tank, high pressure in expansion tank, over-heating, rapid loss of coolant, obvious coolant leaks, and oil loss.

Assuming I don't have these (and I check every week or so) I think a cooling system problem is most likely. So I figure one of these:

1) Heater Valve
2) Airlock
3) SAAB valve failed
4) Matrix blocked

If it is an Airlock how best to check this? I know where the bleed valve is (beside the air filter box) Can I check for an airlock without having to drain the system? Is touching the pipes to see if the correct ones are hot a reliable method?

If it is the SAAB valve will I have to find the broken parts? I mean will I have to take the pipes off right to the thermostat and remove the thermostat and find the busted bits and clear them out?

 

Don't rule out HGF.

Cold air blowing was the first sign of my HGF, then came the overheating and cooling system boiling, but not once did I have oil/water mixture in the oil cap/expansion bottle.

Obviously start with the easy to check stuff, like airblock, faulty matrix etc.

 

Hi I got home tonight and had a chance to look at it a bit more after all the advice on here.

1) The control valve works fine. The dial turns and opens and closes the valve.

2) There is no mayo anywhere, no overheating and no coolant loss.

3) I squeezed the pipes with the expansion cap off and there were no bubbles, but the coolant surged with each squeeze.

I conclude from the above that the valve control is okay, the linkages are ok, there seems no indication of HGF or airlock

That only leaves a blocked matrix or faulty SAAB valve

So I ran the car 7 miles home with the heater set to cold. When I got home I turned the heater on full and warm (not hot) air came out for about 15-20 seconds then ran cold and stayed cold.

I touched all the pipes - Pipes to top of radiator were hot as was the pipe leading to matrix. The Expansion pipe was cold. The radiator return pipe to engine was hotish but less hot than the engine outflow pipe. Both the matrix in, and out pipes were warm and roughly to same extent, maybe the IN pipe was slightly hotter.

To me that means that water must be circulating, ruling out airlock.

So has anyone got any advice?

 

What year is your ZR??? i cant remember the year they began fitting saab valves to the cooling system but i think it may have been 2002 (someone correct me if i'm wrong) if you do have a saab valve fitted to your car then i would certainly check this next, mainly because its quite easy to check and repair. The saab valve could cause hot air to be blown for 15-20 seconds before going cool because only a small amount of water would be making it through the heater matrix and the majority of it would be just going back around the rest of the cooling system.

 

have you bleed the coolant system? really good. just let it bleed more

please check the diagram of the coolant hose with SAAB valve. if valve is stuck, it will push all the coolant towards the heater matrix. if valve is broken/open, hot coolant will still get to the heater matrix. air will not be as hot, but for sure it will be warm enough.

in my opinion, SAAB valve and thermostat do not influence the heater matrix too much. i mean, there is a certain difference between COLD, WARM or HOT.

what's your ambient temperature? did you rev the car a little? take it to the highway, 130km/h with the 3rd or 4th gear. it should get pretty hot and pretty soon :-D

 

I am going to have ago at bleeding it properly on Saturday. I'll let you know how that goes. Thing is there have been no changes to my coolant system, it hasn't been flushed in over a year and the level has never dropped anywhere near minimum, so I can't see how an airlock could get it. But it is easy enough to do so I'll try.

Th engine temperature seems to be normal. Sits just below half way on gauge, the pipes are all hot without seeming over-heated, the fan comes on after about ten minutes. So the main system seems to be circulating. Would that indicate that it is just the heater coolant loop that is functioning incorrectly?

Today there was a little warm air coming through. Hot for about a minute then dropped down to just warm but didn't go totally freezing. Would that mean the matrix must at least be receiving some circulation?

Thanks all the advice I am getting

 

as far as i know, the SAAB valve works as a limiter. when it's cold, it will stay closed so coolant gets pushed entirely through the heater matrix. when hot, it will open, thus letting antifreeze take the straight way and avoid the heater matrix loop.

i have modified my coolant system and i can check about the blower temperatures. i will test it today with and without the SAAB valve. let you know the results.
(if you do get enough and constant warm air, could be the valve being open all the time. but i will get to the bottom of it ;-)

 

That would be great, Thanks

 

sorry for yesterday. it skipped my mind.

however, i did the test today, while ambient temperature was about 24 degrees Celsius, and thermostat was mostly open (75-85 degrees).

in my "summer" coolant system setup, you could say that "MY SAAB" is fully open.
with heater dial on cold and AC on everything was freezing :-D

as soon as i've moved the heater dial to red and turned off the AC, WARM air was coming out.
in about 2 minutes it was almost HOT!
blower setting was on 2 and then 3.

it wasn't winter hot (when i have "MY SAAB" almost closed), but it was HOT more than enough.

so, i would suspect a clogged matrix, but there is also the possibility your water pump got some corroded or broken fins.

good luck.