1990 convertible a/c cycling on heat
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Location: Pacific Northwest USA
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Grant is correct. I'll just add a bit more.
The climate control is designed to refrigerate all incoming first and then heat it as needed. This is to dehumidify the air for comfort. Thus, the compressor is engaged no matter what temp setting the driver asks for....even max heat. The only way to turn off the compressor was to turn the climate control 'off'.
However, turning the system 'off' meant that the fuel wasn't being cooled, as the fuel cooler depends on the compressor being engaged. Jaguar originally didn't worry very much as they felt that it was unlikely that owners would drive around with the system turned off....especially coupe owners, and especially not in warm weather when the climate control was most likely to be desirable.
Somehow, though, the notion hit them that *convertible* owners would very likely be enjoying top-down driving in warm weather. And, more often than not, driving with the climate control 'off'. No fuel cooling.
So......
Circa 1989-90 Jaguar changed the circuit on convertibles so the compressor stays engaged all the time....even with the controls set to 'off'...so the fuel was always being cooled.
Cheers
DD
The climate control is designed to refrigerate all incoming first and then heat it as needed. This is to dehumidify the air for comfort. Thus, the compressor is engaged no matter what temp setting the driver asks for....even max heat. The only way to turn off the compressor was to turn the climate control 'off'.
However, turning the system 'off' meant that the fuel wasn't being cooled, as the fuel cooler depends on the compressor being engaged. Jaguar originally didn't worry very much as they felt that it was unlikely that owners would drive around with the system turned off....especially coupe owners, and especially not in warm weather when the climate control was most likely to be desirable.
Somehow, though, the notion hit them that *convertible* owners would very likely be enjoying top-down driving in warm weather. And, more often than not, driving with the climate control 'off'. No fuel cooling.
So......
Circa 1989-90 Jaguar changed the circuit on convertibles so the compressor stays engaged all the time....even with the controls set to 'off'...so the fuel was always being cooled.
Cheers
DD
The following 2 users liked this post by Doug:
gkazimir (07-12-2015),
Grant Francis (07-13-2015)
#6
The part is replaceable, is still available I think (certainly was a few years ago), and is surprisingly expensive.
Greg
Last edited by Greg in France; 03-21-2016 at 10:30 AM.
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