75ZT Community

raistlin · Posted 05 Jul 2013, 20:48 #1

VeeKay has a temperamental A/C poblem.

Occasionally, the A/C doesn't go cold. The fan works, I've had the gas checked and it is spot on. When it works it gets nice and cold.

I'm wondering if the trinery switch might be intermittent?

Any thoughts please?

takestock · Posted 06 Jul 2013, 06:12 #2

when it is not getting cold, lift the bonnet and feel the two pipes from the a/c. If one is very hot and the other very cold it is likely to be a blend flap problem, mine does it sometimes. Ign off and back on again sorts it. No Idea how to change it so if this is the problem on yours I look forward to a how to.

raistlin · Posted 06 Jul 2013, 08:07 #3

OK Dave, I'll try that out next time it plays up

BingleyThe75 · Posted 07 Jul 2013, 13:41 #4

The most obvious cause I can guess at for your problem would be a fault with the clutch that engages/disengages the air con pump. When you turn the air con on, do the revs dip? If so, do they dip even when the air con isn't cold? If the revs dip whether the air con is hot or cold then the clutch isn't the issue.

raistlin · Posted 07 Jul 2013, 16:50 #5

Yes. I should have said. The A/C loads the engine so the clutch is OK. The compressor is less than a year old.

Duncan · Posted 07 Jul 2013, 19:21 #6

Mr Daves suggestion sounds rather extremely plausible, I wouldn't have thought of that. Maybe a new blend motor would fix it? It doesn't explain why when you check the trinary switch contacts they seem open, though. Maybe the info in the workshop manual is wrong, again!

BingleyThe75 · Posted 15 Jul 2013, 16:29 #7

Have you checked the condition of the condenser? It could be that the condenser is partially blocked by debris. It often happens on modern cars where the condenser is actually in quite a susceptible place for debris from the road. Been a long time since I did any real work on a car in a garage (might be able to tell haha). It could also be the pump itself,if the pump was on it's way out it would still put the engine under load.

raistlin · Posted 15 Jul 2013, 16:52 #8

The compressor is less than a year old so hopefully OK. Might be worth squirting a hose at the condenser though - thanks

Bermudan 75 · Posted 15 Jul 2013, 17:22 #9

Condensor? ubi est?

Mike

Duncan · Posted 15 Jul 2013, 17:36 #10

Condensor is the thing that looks like a radiator, in front of the radiator.

raistlin · Posted 15 Jul 2013, 18:40 #11

DO you think a spirited squirt with a pressure washer would do any harm?

Arctic · Posted 17 Jul 2013, 21:56 #12

raistlin wrote:DO you think a spirited squirt with a pressure washer would do any harm?

Yes if the fins are in a bad state it will blow them out i have seen some real nightmare ones when changing the fans,gunged up oiled ones, birds feathers stuck to them, rows of fins missing,it is reckonned that by 90000 miles each car should have a new one fitted, not my statement i have had one in the shed now for 6 months and i have still not got round to it, dont forget you also have to have a re-gas after so more cost on top of the condenser keep you on your toes dont they these cars but we still love them

Arctic

birds of a feather do stick together :lol:

wonder what was the last thing that went though this birds brain

Duncan · Posted 18 Jul 2013, 17:17 #13

My V6 had no fins on it so got replaced. However I would expect problems with it to make performance a bit poor, not working fine and nothing contrasts.

I wonder if the evaporator temp sensor has gone faulty and is telling the system its already very cold? I've suggested this to other people with ATC (Automatic Temperature Control) faults but never had any feedback. I think the ATC internal diagnostic mode will show what temperature it thinks the evaporator is.

raistlin · Posted 18 Jul 2013, 17:57 #14

I can't remember how to access the ATC diagnostics Duncan.

Duncan · Posted 18 Jul 2013, 18:18 #15

I'm sure someone will know, I don't I'm afraid.

Bernard · Posted 18 Jul 2013, 18:22 #16

I have it noted as 'Hold in the auto button and the button with the chap sitting in a seat logo, then turn on ignition to position 2.'
Never tried it so may be wrong.

raistlin · Posted 18 Jul 2013, 18:33 #17

I'll try that tomorrow. Thanks Bernard.

Mick · Posted 18 Jul 2013, 18:57 #18

ATC Diagnostics atc-diagnostics-t5659.html

raistlin · Posted 18 Jul 2013, 19:08 #19

I KNEW there was a good reason to be a member of this forum :lol:

Thanks Mick.

Bermudan 75 · Posted 18 Jul 2013, 19:46 #20

Cor blimey, good ere init !

Mike :cheers:

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Odd A/C quirk. by raistlin (Page 1 of 2)