blower motor relays getting hot

klf400 · Jul 31, 2010

hi all
anyone know why the 2 relays that control the left and right hand heater blower motors get hot , you would expect a fuse to blow or a fault to show up i have seen this on several p38s
also where the relay plugs in ive seen the plastic slightly melted and scorching on the relay
seems like a need for concern to me
any suggestions ?

rewmer · Jul 31, 2010

Pollen filters clogged ?

tommo138 · Jul 31, 2010

maybe a new fuse box will be needed soon?

fett · Aug 1, 2010

They just draw alot of current , I had the same on a bmw!

I found if I left the ac on and blowers to full and then did lots of stop start errands just using the igntion to turn it all on and off I could blow the fuse after a few times and it also melted the fuse box surrond a bit.

Not sure this applies with all your p38 computer controlled elecrtickery though?

kernowdragon · Aug 1, 2010

Haven't looked at circuit diagram for P38, but most cars use ballast resistors to give different blower motor speeds; if this is also true of P38 then the circuits will generate a certain amount of heat quite naturally, as although resistor is main choke point the whole circuit will effectively be resisitive. As rewmer says things like blocked pollen filters or inoperative blend motors could restrict air flow and increase heat levels.

klf400 · Aug 1, 2010

fett said:
They just draw alot of current , I had the same on a bmw!

I found if I left the ac on and blowers to full and then did lots of stop start errands just using the igntion to turn it all on and off I could blow the fuse after a few times and it also melted the fuse box surrond a bit.

Not sure this applies with all your p38 computer controlled elecrtickery though?

update
further investigation on this p38 has reveald that the fuse box circuit has melted around the one contact on relay no 7 [ this is the yellow one at the front nearest the battery and inner wing
after removeing all the relays and fuses and five screws that hold the circuit cover on its easily visible the damage
pollen filters were changed 2 months ago and are changed yearly ,so a new fuse box needs to be ordered and suspect relays
as i said earlier ive seen this on several p38s scorch marks on relay no 7
and getting rather hot - you would expect a fuse to blow first before melting the fuse board:doh: i
i think the fuse boxs are a problem as i seen instructions how to repair them but i dont think it will ever be the same

overlandrover · Aug 4, 2010

I had the same problem, i carried out the repair procedure on rangerover.net and it sorted alot of problems out including the auto gearbox changing up and down when it wanted. I ran it for a couple of months to check all was well and then bought a new one from believe itor not the main stealer, and it was only £130, and i gave them the chassis number so i know it is the correct one as there are a few changes and depndant on the year the relays are in different places. not so clear when buying a copy part or off ebay.

klf400 · Aug 6, 2010

overlandrover said:
I had the same problem, i carried out the repair procedure on rangerover.net and it sorted alot of problems out including the auto gearbox changing up and down when it wanted. I ran it for a couple of months to check all was well and then bought a new one from believe itor not the main stealer, and it was only £130, and i gave them the chassis number so i know it is the correct one as there are a few changes and depndant on the year the relays are in different places. not so clear when buying a copy part or off ebay.

re fusebox
microcat comes up with 3-4 different part numbers for petrol as well as diesels
so i think you would have to be carefull if fitting s/h as the amount of different part numbers, if so make sure its not allready melted

blower motor relays getting hot

klf400

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rewmer

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tommo138

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fett

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kernowdragon

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klf400

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overlandrover

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klf400

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