Mk7 Heater/Air con problem

[vivcol]

I have a 08. 2.2 130 . Which is a 350M based motorhome. It has Manuel A/C. Problem is that the heater still puts hot air into the cab even when turned to cold and the A/C is on. The A/C has been checked and regassed. The local dealer says its likely that a flap is stuck open in the heater box. This would mean a complete dashboard strip and maybe replacing the unit too, probably £1k. When the problem started I noticed that the vacuum pipe between the Heater Control Unit, or Air Con Valve as I've seen it called, and the heater, had sucked flat and welded itself together. Probably cooked by the Turbo. I cut the flat bit out and replaced it with some brake line as suggested elsewhere. Didn't sort it though.
I would very much appreciate some help with 2 questions.
1. Does the Heater Control Unit actually isolate the hot water from the heater when off as in the old days? Both pipes running through the bulkhead to the heater on mine get and remain hot when control is set to cold. That used to mean the valve had failed.
2. Please does anyone have any info to help me strip the dash and heater unit out if I've really got to do it. It doesn't look fun.
Many thanks

[Guy88]

with the engine off but ignition on can you hear a motor working when changing the temp?#

the vacum pipe going into the cab is for the recirculate settings

if you have a vacuum controled valve in your coolant feed pipes then when the heater is on full cold this should be operated to divert the coolant

[v8dave]

Where are the controls set?

My a/c gives cold air when the direction control is turned fully anticlockwise to give air at face level. If it is set to feet or screen I get warm air.

Dave

[vivcol]

Many thanks Dave. Guy, I tried your suggested test and I can hear a motor operating when I turn the temp control either way. So I guess that means that the Flap motor is operating? Hopefully the flap is still attached to it. Also the' Heater Control Valve' does have a vacuum line in to what could be a diaphragm . Is there enough power there to operate a valve? As you know there is no electrical power there. I do suspect that valve . Thanks for your help . Colin

[martynx]

Many thanks Dave. Guy, I tried your suggested test and I can hear a motor operating when I turn the temp control either way. So I guess that means that the Flap motor is operating? Hopefully the flap is still attached to it. Also the' Heater Control Valve' does have a vacuum line in to what could be a diaphragm . Is there enough power there to operate a valve? As you know there is no electrical power there. I do suspect that valve . Thanks for your help . Colin

Hi did you manage to fix this?

[747_727]

Did you manage to get yours fixed, mine has given up today, air con comes on but only warm air coming from vent I can hear the heat mixer motor moving.

[martynx]

Sticky flap in heater box leads to heater servo flaps motor seizing. New servo motor , 90 quid from ford , that's what fixed the one I worked on anyway

Not sure how long for though but full fix is replacement heater box. There's a detailed thread on on here somewhere inc part number etc.

[ake]

Did you manage to get yours fixed, mine has given up today, air con comes on but only warm air coming from vent I can hear the heat mixer motor moving.

Strip and clean the temp control knob, the track inside it corrodes and the heater defaults to a mid way setting.
Mine has been perfect for months since I cleaned mine

[747_727]

Did you manage to get yours fixed, mine has given up today, air con comes on but only warm air coming from vent I can hear the heat mixer motor moving.

Strip and clean the temp control knob, the track inside it corrodes and the heater defaults to a mid way setting.
Mine has been perfect for months since I cleaned mine

Sorry I'm a little impatient

I will check that, did you motor move before you checked the tracks? Mine does move when I turn the control knob.

[ake]

Did you manage to get yours fixed, mine has given up today, air con comes on but only warm air coming from vent I can hear the heat mixer motor moving.

Strip and clean the temp control knob, the track inside it corrodes and the heater defaults to a mid way setting.
Mine has been perfect for months since I cleaned mine

Sorry I'm a little impatient

I will check that, did you motor move before you checked the tracks? Mine does move when I turn the control knob.

It moved about 1mm, and if I dismantled it, and put it back together with the lever at one end, as soon as it was plugged back in and powered it would go back to the middle

[747_727]

I think my motor has full movement on it. I took the cover off and seemed to have full travel when I turned the control knob, it also activated the microswitch on the drivers side when turned to cold.

I've checked the vacuume at the diaphragm at the bulkhead and that is work in I also bypassed the little unit behind the headlight and that made no difference.



Has it been known for the diaphragm to fail?

It's strange because my ac was working yesterday but no cold air today, but the ac compressor runs and I had it regassed last year.

Mine has always blown warm air when in cold but the AC would always eventually come through, but to day there is just warm air with the ac running.

Any ideas?

[Booster76]

Can someone advise of a supplier for this part servo motor or part number please I have faulty unit, but cant find the thread on here many thanks Dave.

[martynx]

It's available from Ford separately.