Doctor Diesel

Education for The Doctor

Air conditioning
Air conditioning
I have just read your comment “Cold Comfort” to Geoff King’s letter (Diesel Car 331) and I agree that the winter months can be unpleasant in the morning driving a diesel car. It has been for me, using diesel cars since the late 1970s in the UK and in Scandinavia, where the temperature can regularly be lower than minus 10 degrees Celsius. However, for several years now, I have no longer suffered from this cold discomfort. No, I am still driving a diesel car, but, quite by accident, I discovered that my Citroën Xsara Picasso’s air conditioning system uses a reversible heat pump, which produced cold air in the summer and warm air in the winter. This happened when I accidentally knocked the A/C switch on once whilst I was de-icing the car and found warm air was flowing into the car. It has now become routine in the winter to switch the A/C on after starting the engine. Warm air is produced after 20 to 30 seconds if the outside temperature is not lower than minus 10 degrees Celsius. It takes longer as the temperature drops, and very little heat is produced below minus 25 degrees. Once the cooling water is heated, the A/C may be switched off. I calculate that, for this procedure, about 20 to 30 pence worth of additional fuel is used, which will not break the bank. I understand that several manufacturers install similar types of air conditioning and I suggest that your readers (who do not have heated garages) may investigate this possibility in order to alleviate their winter suffering! Many thanks for an excellent magazine and help.
Mohamed, Sheffield.

That is really interesting Mohamed, and what you have told me is an education! I was until now totally unaware of this. Amazing! I shall have to look into this some more and find out which other manufacturers use the same sort of unit. What’s amazing is that nobody else seems to know about it. Is the use of the A/C in this way quite correct and does it have no ill-effects, I am wondering – not to infer that you shouldn’t be doing it, but why isn’t it mentioned in the owner’s handbook, one wonders? I’m lost for words just now, and I’ll probably come back to you when (if?) I find out a bit more. Many thanks for your letter, and I’m glad that you enjoy the magazine. I’m sure that Ian and the team will be pleased to know that their efforts are appreciated by readers like yourself!
Regards, Doc Diesel

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