hot/cold heater problem - any thoughts ?

[eddieedmo]

we have been away last week walking in Shropshire and a couple of times the heater would blow hot and no matter where the temp knob was would be hot.Then would be ok.On the way back it was hot and then went cold and hot again and stayed hot !Temp control knob at cold and had no effect when turned.
Has any one had this problem or know what it could be.Is it a dodgy temp control switch ? how can it be tested ?
Thanks in advance.
Car ran great apart from this , over 800 miles @ 31.5mpg !

Nick []

 

[Catamax944]

It's probably the plastic clip from the left side linkage rod ,common fault .
Look here ,bottom of page http://www.clarks-garage.com/shop-manual/hvac-01.htm
On my car the previous owner fixed it with a zip tie and i left it like that because it still works great after many years.

 

[eddieedmo]

Thanks for that will have a look , my car is climate control not A/C is it the same layout ?

Nick []

 

[Catamax944]

yes ,same layout , late 944's are only with or without climate control, only early ones can have A/C .

 

[Frenchy]

Also check the blue / black valve in the vacuum line under the bonnet it will be at the bulkhead.

 

[eddieedmo]

check all linkages ,vac lines etc and all seem ok , fiddle about with temp control switch and sometimes it works and sometimes it does't so seems to be switch problem.on cold now so keeping there with our summer making an appearance !
Has anyone had these apart or fixed ?

Nick []