Heating Warm One Side Not The Other?

[isSport200]

I have read on here somewhere before about the problem with the heater being hot on the drivers side but cool air on the passenger side. I have tried flushing the system twice now and replaced the coolant and thermostat , I still have the same problem is there anything else that can be done before the matrix gets replaced?

[maddywork]

I have exactly the same problem, since last year when it snowed real bad.

Would love to hear about a possible solution.

[Lance]

It sounds like there is a sticking flap inside the heater box. If you are getting warm air inside the car and the engine runs at a normal temperature then the thermostat and cooling system is working fine.

Inside the heater box the warm air is controlled by flaps inside the heater box. With the engine off but the ignition on you can hear the flaps move when you adjust the directional controls on the dashboard.

It is a big job to get the heater box out I suspect as it's buried way in the back of the dash, but that's where I'd be looking.

[steve2006]

I agree with Lance, the exploded diagram for the heater system shows only 1 heater matrix so the problem lies with a servo motor/flap fault.

There are several of these controlling both the hot and cold air mix and the direction of the air flow.

It's a major strip down to get to these so a workshop manual is a good idea, CDROM copies are normally on Fleabay for a few pounds.

[lex2oos]

I disagree.

there is only one flap in the heater unit, so if it is stuck, BOTH sides should be blowing cold air. I say it is still related to heater matrix. I had the same problem. Since my car is LHD I had cold air at drivers side and warm at passenger. I removed heater matrix and took it home, flushed with vinegar and citric acid. now it is alot better, but will see what happens when temperatures will fall lower than 0 degrees celsius.

good luck