P38A Fan speed on the heater
- Thread starter Dopey
- Start date
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brianp38dse
Well-Known Member
- Posts
- 20,067
- Location
- heathrow
Funny, mine is the same never gave it a thought spends most of its time in auto
- Posts
- 1,520
- Location
- Buckinghamshire.
Mine's a bit like that too. Wheeling round and round without doing much.
Interestingly, when I popped the dial off to change the bulb, it started working perfectly. You could try that!
Interestingly, when I popped the dial off to change the bulb, it started working perfectly. You could try that!
- Posts
- 58,170
- Location
- Preston Lancs.
Fan speed is dependent on temperature as measured by sensor on matrix inlet pipe. Even if you set fans at full speed they will not come on at full speed until the coolant temp reaches a certain level.
- Posts
- 19,297
- Location
- Buckinghamshire, UK. ('95 DT)
Mine works perfectly but I almost never take it out of Auto except when I press Prog.
Setting fan speed by turning adjustment knob overrides all automatic behavior. Turn it to maximum speed and relays in bower motors are engaged giving full voltage.
- Posts
- 58,170
- Location
- Preston Lancs.
- Posts
- 3,878
- Location
- Near Heathrow.
Clean contacts. Then check HEVAC sensors.... all of them. Then turn knob slowly so ECU can catch up with it.
martyuk
Well-Known Member
- Posts
- 824
- Location
- Swindon, UK
If you have to turn the knob loads of times, then chances are it's the contacts on the board are dirty and the wiper on the back on the rotary knob (the clear bit inside - not the cover that you pull off - so have to dismantle the unit.
It's one of the things I do on all the HEVAC units that I service, and pretty much all of them are tarnished, and the tracks on the board are dirty.
To clean the board, I use contact cleaner/isopropyl alcohol, and a cotton bud. To clean the metal wiper, I use high grit sandpaper, or emery cloth.
On my website, on my 'Technical Information' page there's instructions for installing my pixel fix shows the unit being stripped apart and the track on the board/and the wiper that gets dirty.
It's one of the things I do on all the HEVAC units that I service, and pretty much all of them are tarnished, and the tracks on the board are dirty.
To clean the board, I use contact cleaner/isopropyl alcohol, and a cotton bud. To clean the metal wiper, I use high grit sandpaper, or emery cloth.
On my website, on my 'Technical Information' page there's instructions for installing my pixel fix shows the unit being stripped apart and the track on the board/and the wiper that gets dirty.
Last edited:
P38Penguin
Active Member
- Posts
- 305
- Location
- West Midlands
I had when I first got mine. Put it on max and it was like an asthmatic snail. Took both cabin filter covers off and there was that much crud and rubbish built up it was horrendous. New filters and a goot blast with the vacuum and all good.
