Air Con passes all the tests but still won't work!

Blotty · 13th November 2023, 20:55

I hope one of you brainboxes out there can help solve my problem.. I have a 2002 diesel which i bought last year and i have no idea when the air con last worked. All fuses and relays check out, the fan works perfectly and the clutch engages nice and freely when demist is selected. I bought a cheap pressure gauge to see what might be happening when i try to operate the system and the results just confuse me! The static pressure is around 41psi in both sides, and when i press demist (engine running), the low pressure drops to about 31 and the high pressure just goes to about 48psi. The pipes do not change temperature at all and, as you've already guessed, no cold air at all.

Can anyone please give me some pointers as to what may be happening here as i can't see any point in going for a regas if i have some kind of problem that is preventing refrigerant circulating. I'd really like to solve the problem myself as i'm terrified of throwing myself at the mercy of a garage who might turn out to be useless! Many thanks.

SD1too · 14th November 2023, 07:58

Hello Carolyn and

to the club.

As your compressor is engaging you must have sufficient residual refrigerant pressure but maybe not enough to produce cooling. Another possibility is that your condenser (in front of the radiator) has seriously deteriorated.

I'd say that you've done all the necessary preliminary checks but I'd recommend that you don't go to a garage offering regassing and certainly not the fast-fit outfits. Instead, search for automotive air conditioning services near your town and choose a self-employed mobile specialist.

A good one should extract your refrigerant to check the amount, inspect the system (particularly the vulnerable condenser) and perform a nitrogen pressure test to check for leaks. Only then should your car be recharged with the correct weight of refrigerant including a little special lubricating oil.

Air conditioning should be used periodically all the year round to avoid seal shrinkage and loss of pressure (which may be what's happened to your car).

Do come back to us if you have any further questions.

Simon

Blotty · 14th November 2023, 20:20

Thanks for the reply Simon, i try to be as hands on as possible so i've been reading the forums and learning about the air con so i can avoid having the Rover looked at by someone not up to the job (lots of people on here seem to have had problems with garages giving wrong diagnoses..). The condenser looks a little worse for wear, but not as bad as some of the pictures on this site - wouldn't an ageing condenser just give poor cooling and consequently reduced cold air output, as opposed to the zero cooling that i currently get? I imagine the condenser is just like the cooling system radiator, or is that a bit simplistic?

I'm hoping to get someone to come out and regas it, or alternatively i will happily take it to a specialist, but finding someone up here in the north west is proving very challenging!

SD1too · 15th November 2023, 07:23

Quote:

Originally Posted by Blotty

... wouldn't an ageing condenser just give poor cooling and consequently reduced cold air output, as opposed to the zero cooling that i currently get?
I imagine the condenser is just like the cooling system radiator ...

Yes, you're right on both questions. It's just that I would expect some cooling effect at this time of year.

Simon

Blotty · 16th November 2023, 08:45

I'll try and find a reputable specialist and see how i get on. Cheers Simon

13th November 2023, 20:55	#1
Blotty Newbie Rover 75 Saloon Join Date: Nov 2023 Location: North West Posts: 3 Thanks: 0 Thanked 0 Times in 0 Posts	Air Con passes all the tests but still won't work! I hope one of you brainboxes out there can help solve my problem.. I have a 2002 diesel which i bought last year and i have no idea when the air con last worked. All fuses and relays check out, the fan works perfectly and the clutch engages nice and freely when demist is selected. I bought a cheap pressure gauge to see what might be happening when i try to operate the system and the results just confuse me! The static pressure is around 41psi in both sides, and when i press demist (engine running), the low pressure drops to about 31 and the high pressure just goes to about 48psi. The pipes do not change temperature at all and, as you've already guessed, no cold air at all. Can anyone please give me some pointers as to what may be happening here as i can't see any point in going for a regas if i have some kind of problem that is preventing refrigerant circulating. I'd really like to solve the problem myself as i'm terrified of throwing myself at the mercy of a garage who might turn out to be useless! Many thanks.

14th November 2023, 07:58	#2
SD1too Doesn't do things by halves Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007 Location: Former Middlesex Posts: 20,372 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	Hello Carolyn and to the club. As your compressor is engaging you must have sufficient residual refrigerant pressure but maybe not enough to produce cooling. Another possibility is that your condenser (in front of the radiator) has seriously deteriorated. I'd say that you've done all the necessary preliminary checks but I'd recommend that you don't go to a garage offering regassing and certainly not the fast-fit outfits. Instead, search for automotive air conditioning services near your town and choose a self-employed mobile specialist. A good one should extract your refrigerant to check the amount, inspect the system (particularly the vulnerable condenser) and perform a nitrogen pressure test to check for leaks. Only then should your car be recharged with the correct weight of refrigerant including a little special lubricating oil. Air conditioning should be used periodically all the year round to avoid seal shrinkage and loss of pressure (which may be what's happened to your car). Do come back to us if you have any further questions. Simon __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.

14th November 2023, 20:20	#3
Blotty Newbie Rover 75 Saloon Join Date: Nov 2023 Location: North West Posts: 3 Thanks: 0 Thanked 0 Times in 0 Posts	Thanks for the reply Simon, i try to be as hands on as possible so i've been reading the forums and learning about the air con so i can avoid having the Rover looked at by someone not up to the job (lots of people on here seem to have had problems with garages giving wrong diagnoses..). The condenser looks a little worse for wear, but not as bad as some of the pictures on this site - wouldn't an ageing condenser just give poor cooling and consequently reduced cold air output, as opposed to the zero cooling that i currently get? I imagine the condenser is just like the cooling system radiator, or is that a bit simplistic? I'm hoping to get someone to come out and regas it, or alternatively i will happily take it to a specialist, but finding someone up here in the north west is proving very challenging!

16th November 2023, 08:45	#5
Blotty Newbie Rover 75 Saloon Join Date: Nov 2023 Location: North West Posts: 3 Thanks: 0 Thanked 0 Times in 0 Posts	I'll try and find a reputable specialist and see how i get on. Cheers Simon