P38A Prog question.

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On my 2000 4.6 Thor pressing program gets the front and rear screen and mirror defrosters going and the heater air going to the screen; but, the fan doesn't crank up in speed until the water temp is up a bit, the changeover is very noticeable from a moderate fan speed to "full-blast" without any human intervention. The cars handbook says that the prog function selects the most suitable fan speed and the front screen heater is switched off after 4 minutes and the rear after 16. So when the car is cold I guess there is no point in blowing freezing air at a screen you are trying to defrost with the heating elements. It sort of makes sense that once the water temp comes up it is only then worth turning the fan speed up I suppose.
I would not have thought such an old car would be so sophisticated though.
 
DanClarke said:
On my 2000 4.6 Thor pressing program gets the front and rear screen and mirror defrosters going and the heater air going to the screen; but, the fan doesn't crank up in speed until the water temp is up a bit, the changeover is very noticeable from a moderate fan speed to "full-blast" without any human intervention. The cars handbook says that the prog function selects the most suitable fan speed and the front screen heater is switched off after 4 minutes and the rear after 16. So when the car is cold I guess there is no point in blowing freezing air at a screen you are trying to defrost with the heating elements. It sort of makes sense that once the water temp comes up it is only then worth turning the fan speed up I suppose.
I would not have thought such an old car would be so sophisticated though.
Click to expand...
I agree with all of that except the mirrors are always heated regardless of settings which is why they fail so often.
 
Just tried it again, thin layer of soft ice/slush on front and rear screens. Started her up, book symbol on,and hit prog. No increase in fan speed, both front and rear switch lamps came on, prog displayed on the screen, fan direction lamp to windscreen came on. Evidence of rear screen heater working within 30 secs, nowt on the front. Left it 5 minutes, still no hfw or higher fan speed so turned prog off.
Thought I had my assistant today to help check things but she's been called into work.After I had dropped her off
I did notice one thing though. The A/C button lamp was off so ac was on, being tall I can't see that lamp without leaning over and down.
Could that being on stop the hfw working? Can't see that but you never know:oops:.
I also pressed prog again and the fan speed went to high straight away.
 
Flossie said:
Just tried it again, thin layer of soft ice/slush on front and rear screens. Started her up, book symbol on,and hit prog. No increase in fan speed, both front and rear switch lamps came on, prog displayed on the screen, fan direction lamp to windscreen came on. Evidence of rear screen heater working within 30 secs, nowt on the front. Left it 5 minutes, still no hfw or higher fan speed so turned prog off.
Thought I had my assistant today to help check things but she's been called into work.After I had dropped her off
I did notice one thing though. The A/C button lamp was off so ac was on, being tall I can't see that lamp without leaning over and down.
Could that being on stop the hfw working? Can't see that but you never know:oops:.
I also pressed prog again and the fan speed went to high straight away.
Click to expand...
Aircon is normally always on and does not affect the Program operation.
 
pwood999 said:
On mine in Prog mode, the fans only go to high speed once there's actually warm coolant going to the matrix.
Click to expand...
That makes sense. I'm doubting my memory now but I swore they came on full speed straightaway in the last cold snap with a frost , before Xmas iirc. Heated windscreen was a blessing at -5 at 5am.
Next check is to see if the relay is operating I guess.
Does anyone know the wires to prod with my dmm between fusebox and screen to see if I have power?
The stud with the two cables under the scuttle is the ground for them isn't it? .
 
Flossie said:
That makes sense. I'm doubting my memory now but I swore they came on full speed straightaway in the last cold snap with a frost , before Xmas iirc. Heated windscreen was a blessing at -5 at 5am.
Next check is to see if the relay is operating I guess.
Does anyone know the wires to prod with my dmm between fusebox and screen to see if I have power?
The stud with the two cables under the scuttle is the ground for them isn't it? .
Click to expand...
Both connections to the screen are under the plenum cover.
 
Prog without working Aircon on Otto. 2 screens but seat heaters manual. Fan runs medium, then kicks to high after about 1/2mile. Handbook symbol always on, suspected corrosion in the manual fan control bit, plus nanocom reports stuck flaps so I suspect stripped gears in the controllers.
 
Forgot about this.
The two relays in the fusebox are, I assume?, one for the front and one for the rear? Swopped them over and the rear still works but the front still doesn't.
Haven't had the time to take the scuttle off as yet, stuff keeps breaking in the house:mad:.
 
2 relays, one for each side of the screen. Power to the first relay provides the power to switch the second relay. Both sides consume 35A if i recall
 
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