mozzerscoob

iTrader: (1)

Guys need some help before I set fire to the car. I have brought a 2001 ford fiesta 1.3 as a work horse and the heating in the car only blows cold. I have replaced the water pump , thermostate and the heater control valve. I have also flushed the coolant system and the heater matrix and run the car up to the coolant fan kicks in removing all the air out the system but still it only blows cold. I have checked the voltage to the heater control valve and it ranges between 0-1 volt which should default the system into hot air only into the car but I get on a short blast for approx 10-15 seconds when the engine is warm then Back to cold again .Any ideas much appreciated

ALi-B

iTrader: (1)

Fitted the heater valve the right way round?...I have once fitted one upside down so the inlet and outlet hoses were reversed....suffice to say it didn't work

I assume it was a brand new heater valve of a known brand (delphi etc). Lots of cheap crap on ebay which may/maynot work.

Heater panel itself can go faulty too. You need a oscilloscope to check the voltage waveform properly, but a analogue multimeter will probably do the job though.. Generally speaking, the one wire on the valve should should pulse between 0volts to 14volts (engine running) once every 3 seconds. Current should be just under one amp (about 0.8A) and pulse in the same manner.

The panel provides the earth path. So the valve always has a live supply.

Now, this is the bit I can't remember, but it should be the same as the Jags (which suffer the exact same issue with these valves)...the valve is only powered to shut it (cold). So with it open circuit (connector disconnected) it should open and give you hot air.

Hope that helps

mozzerscoob

iTrader: (1)

Hi yes a new TRW valve fitted no cheap crap off eBay and I only have 0-1 volts at the 2 pin plug so should default the valve into hot air only but still no good and yes pipes fitted the correct water flow inlet on solenoid side so I'm still stumped. If the engine is warm and fan motor inside car is off both inlet and outlet hoses on the matrix are hot but when I switch the fan on I get hot air for approx 10-15 seconds then it goes cold again so I rechecked the matrix hoses and inlet is hot and outlet is barely warm to the touch