1990 XJS A/C blower motor speed problem
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Louis Pullara Jr (10-24-2014)
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The blower speeds on your model are controlled by the climate control ECU and the circuit board inside each blower assembly. The circuit board has a transistor and a couple diodes...or some such. Nearby the circuit board is a relay
From memory the highest speed comes from the relay being energized. All lower speeds are controlled/commanded from the ECU by varying resistance to ground.
We have the Delanair Mk III diagnostic manual on the web site somewhere. If you're interested in doing your own testing I'll try to find it for you. You'll need a volt/ohm meter.
Cheers
DD
From memory the highest speed comes from the relay being energized. All lower speeds are controlled/commanded from the ECU by varying resistance to ground.
We have the Delanair Mk III diagnostic manual on the web site somewhere. If you're interested in doing your own testing I'll try to find it for you. You'll need a volt/ohm meter.
Cheers
DD
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Louis,
I suspect this is the usual and very common problem of the Darlington Transistor having failed. Is the speed high on both blowers (L&R) or just high on one side?
The Darlington Transistor is very well documented, you'll find lots of threads on many Jaguar Forums relating to this. Just spend 15 mins doing a search and read on the issue. If it is the problem, you can buy a compatible transistor from any good electronics store.
Good luck
Paul
I suspect this is the usual and very common problem of the Darlington Transistor having failed. Is the speed high on both blowers (L&R) or just high on one side?
The Darlington Transistor is very well documented, you'll find lots of threads on many Jaguar Forums relating to this. Just spend 15 mins doing a search and read on the issue. If it is the problem, you can buy a compatible transistor from any good electronics store.
Good luck
Paul
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Louis Pullara Jr (10-29-2014)
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