Heat blowers running cooler on passenger side

[Rick-sta]

Hi all,

Here's a problem we've had on my dad's 75 for a few years now. The heaters blow cooler on the passenger side. Started a few years ago when the heaters would blow pretty much completely cold on the passenger side even with the temp settings set to high on both sides (car has dual climate control). Removed the heater matrix and cleaned it out which didn't make much difference.

I then replaced it with a brand new one which improved things however it still only blows slightly warm on the passenger side whereas it blows very hot on the driver's side. This was about 2 years ago. Both pipes running to the heater matrix get very hot to the point you can barely touch them.

Hold the revs over 3k when the engine is up to running temp and the heater blowers on the passenger side get slightly warmer but still no way near as hot as the driver's side. Again this is with the temp set to high on both sides.

The engine when up to temp runs at around 82oc. Has the inline stat fitted.

Any ideas, is there anything mechanical that may not be working on the passenger side?

This is a problem I've not had on any of our other 75's or ZT's. Both my ZT's blow equally hot on both sides and never had this issue on my ZT-T or 75 either.

[roverbarmy]

These diagrams may help:-
https://rimmerbros.com/Item--i-GRID001588
read with this thread:-
https://the75andztclub.co.uk/forum/s...d.php?t=287565
The blend motor being on the left/near side of a UK car. Blend motor is No.3 on drawing.

[Rick-sta]

Cheers Mike, done the self test on the AC panel and only brings up the usual 21 and 22 sunlight sensor error codes, nothing else.

As Nick Greg asked on that thread, does no fault codes mean the blend motors are definitely working?

[Number 6]

Originally Posted by Rick-sta

Cheers Mike, done the self test on the AC panel and only brings up the usual 21 and 22 sunlight sensor error codes, nothing else.

As Nick Greg asked on that thread, does no fault codes mean the blend motors are definitely working?

Bit of a long shot but did you give it a damn good bleed,When I cleaned my matrix out it took a couple of good goes to get the air out. I also had the inline stat fitted, dont know if that makes a difference to bleeding...........Just another thought, have you tried to remove the passenger side panel to access the passenger side of the Matrix to see if it as hot as the drivers side??

[Ivar Birkeflot]

I have same issue on my 1.8 non-turbo Left Hand Drive in Norway. Not a big issue thus the car is stored for winter, but fires right up, and gets 9 o´clock warm in a few minutes. Hot went on drivers side, and colder on passenger side. So follow this thread if any good respones

[trikey]

Originally Posted by Number 6

Bit of a long shot but did you give it a damn good bleed,When I cleaned my matrix out it took a couple of good goes to get the air out. I also had the inline stat fitted, dont know if that makes a difference to bleeding...........Just another thought, have you tried to remove the passenger side panel to access the passenger side of the Matrix to see if it as hot as the drivers side??

I would agree with this, I had the same issue with Deb's ZTT, ran around for about a year with an 'average' heater, backflushed the system and re bled and now its the best heater out of all our cars.

[roverbarmy]

You could try setting the setting to high and then to low several times to see if that frees anything off. Also the recycled and outside air control. I did this with my car when I first got it as the previous owner (elderly gent who had previously lost his wife) may never have used the temp control on the passenger side. My good lady had complained of her heater not getting warm. After a few high/low temp cycles, it seemed to right itself. I use the same principal with lots of parts on the old Rovers, like moving the windows up and down, locking and unlocking the doors and boot, both manually and electronically with keys and buttons on a regular basis. Saves all those bits getting seized up. (not forgetting to lube locks with graphite, and silicone spray on the window slides and door seals).

[StewartIngram]

Surely the controls have no effect on water control through the matrix? Only the air control - ie flaps - is changed.

[Rick-sta]

right just got back round to taking another look at this problem today.

Have bled the coolant system, just constant coolant comes out of the bleed screw and no air bubbles, also got it up to temp with the expansion tank cap off and no rush of bubbles or anything there either.

How do I access the passenger side of the heater matrix? took the trim panel off and looks like there's no way of getting to the matrix from that side (see pic attached).

The passenger side only blows about half as warm as the driver's side (driver's side gets nice and hot). But if I adjust the temp down to low on the passenger side it does change to blowing cold air out, adjust the temp back to high and it goes back to blowing the warm air out.

What's the best way to back flush the heater matrix? I see one of the coolant hoses runs from the heater matrix to the pipework around where the FBH would be. Should I disconnect the pipe there and flush it through with a hose pipe?

[Cable Tie]

Dishwasher tablet crumbled up and put into the system normally does the job rick,had a couple that had this problem and its unblocked the matrix when it got back to being hot just flush the system by dropping the bottom hose off and refilling good luck