How to Replace the Heater Resistor

[Dog_Book]

Originally Posted by Butch1

Me and husband really are learners when it comes to fixing our V40, but THANKS to Gatos and his photo's it's all done for £2.89 no garage bill and a bit of a laugh had, can't thank you enough

Hey just remember i love him more than you!

[gatos]

Originally Posted by Butch1

Me and husband really are learners when it comes to fixing our V40, but THANKS to Gatos and his photo's it's all done for £2.89 no garage bill and a bit of a laugh had, can't thank you enough

Glad I could help and thanks for your kind words. I was a learner too 2 1/2 years ago and I am still learning todate...... If I can do some of the things I do on cars, then so everyone else can do so too with some basic tools....

Originally Posted by Dog_Book

Hey just remember i love him more than you!

lol. I love you too Doggie .....

[bilfish]

Many thanks Gatos for your help, fixed heater today excellent post. BTW I replaced the flying saucer from Maplin couple of quid, rather than new resistor unit volvo wanted £50!!

[Pete_c20]

I've replaced the transistor on the heatsink in the past and it cured the intermittent problems with the air blower. Unfortunately I can't remember if the transistor had an insulating washer between it and the heatsink. What I would say is that if the transistor does have some form of insulating washer then it needs to be put back in with it when the transistor is re-newed. Don't replace an insulating washer with thermal paste as the paste will eventually migrate and in time the transistor will electrically contact the heatsink and may cause further problems. If there is no washer then it's electrical contact may be important to its operation.

Operation of the Climate control pack (CCM) pack.

Whilst troubleshooting mine I noticed that there were no signals going to the transistor on the heatsink. So my first conclusion was that the CCM output driving the transistor had died. Volvo quoted £406 (+vat?) for a new circuit board. However it would seem that the CCM, when first turned used, sends out a signal and if the MJ802 transistor doesn't respond, it shuts down the signal driving it. This could be seen on an oscilloscope.

Replacing just the MJ802 transistor fixed the problem and it's been fine since.

The MJ802s probably blow due to poor heatsinking. Like Mike Alder I seemed to recall it being a good idea to increase its heatsink area. If it goes again that's what I'll do.

When people talk about replacing the 'heater resistor' do you mean that you're actually replacing the 'flying saucer' thingy on the knobbley metal bit?

[PaulJohn]

Thanks for the great how-to. After my blower went full speed, I took my S40 to the dealer who advised me to change the complete climate control unit à raison of €500.. Now I bought a new resistor found http://volvoforums.com/forum/volvo-s...-module-67765/ and changed it with a total cost of just €1,50 and the blower works great again.

Regards,
PaulJohn
Nehterlands, Amsterdam

[springer6]

Originally Posted by jblomeyer

I have speradic (spasdic) fan blower. Periodically slow, then full blast. Can the resistor be repaired ??

Hi, I have a slightly different problem on my 2003 1.8 S40. The fan does not work at all, also no lights behind the fan control or direction control. fuses are ok.
Could it be the heater control unit?
Any suggestions would be much appreciated.
Thanks
Springer6

[johnspex]

Hi, my 98 v40T4 blows at all the right speeds and the aircon is fine but the air coming out of the heater is tepid at best. The temp guage shows about 80-90 degrees and will occasionally rise to 100 at which point the coolong fan cuts in. But still I only get warmish air. Any answers?

[lokibaz]

Thank you so much for this, My heater stopped working all together and I have now fixed for £2.90 (cost of a MJ802 transistor from ebay) plus the cost of a new cabin filter. This fix also solved another issue I was having whereby when the heater was set to number 3 or below it would cause interference on the car radio.

[gatos]

Originally Posted by lokibaz

Thank you so much for this, My heater stopped working all together and I have now fixed for £2.90 (cost of a MJ802 transistor from ebay) plus the cost of a new cabin filter. This fix also solved another issue I was having whereby when the heater was set to number 3 or below it would cause interference on the car radio.

Glad I could help

[blairs40]

hey bro , long time , so my heater doesn't turn on straight away when I turn the knob ..... maybe 5 -10 minutes it will come on and work fine ... turn car off , turn back on again and may start straight away or may not ... so thought ahA!!! the stinkin resistor/transisitor thingy .... went and bought replacement , ... pulled out old resistor and .... hmmmmm bloody different .... see attached pic ....
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