DSE Air Con questions

Right here goes,

Have just replaced the condensor rad (big hole) on my 1997 P38 as the air con hasnt worked since buying the car. Regassed fine, found the high pressure switch wouldnt work the fans. Have replaced the switch fans now sort of work...........I guess my question is "how does the system work ?"
My compressor clicks in & out whilst ticking over, is this normal, how are the fans supposed to work, when are the fans supposed to work, should they start running when the ac is switched on then get faster as the heat/pressure increases ?
BTW the car gets nicely chilled but the engineer was concerned about the frequency of the compressor cutting in & out.

Thanks in advance for your wisdom !!

Steve

Oh yeah & the book symbol comes on when I press recirq

Hello Steve, Just some basic observations.

javars said:

I guess my question is "how does the system work ?" My compressor clicks in & out whilst ticking over, is this normal,

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Yes - 3 cycles per minute would be about right - more, prolly means its not fully charged - less, prolly means "baby its cold outside" so not so much refrigeration required.

how are the fans supposed to work, when are the fans supposed to work, should they start running when the ac is switched on then get faster as the heat/pressure increases ?

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I'm not aware of speed control on these fans, so -


No, the fans respond to the high pressure circuit safety switch, and that pressure will be too high on very hot days, or idling in traffic with an inefficient cooling system or the viscous fan not working properly.

All these conditions would contribute singly or combined, to the condensor not cooling the refrigerent suificiently so the gas pressure remains too high on the high pressure side, the fans come on, the condensor is then further cooled by the supplimentary fans.



The pressure then drops and the fans go off.



The fans are also engaged by a temp switch measuring coolant temperature, so if ,for some reason, the cooling system cannot cope, the fans come on to assist cooling the rad. This is independent of the aircon system

BTW the car gets nicely chilled but the engineer was concerned about the frequency of the compressor cutting in & out.

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Was the frequency too high or too low? get him to explain his concern!



Hope this helps?

Ramon
Vintage Model Airplane and Rover SD1 3500cc Twin Plenum Vitesse

Thanks for the info, just got a copy of rave..........imformation overload !