Air Con Pressure Switch

IGH · 11th March 2015, 20:02

A fault on the air con has been traced to the tri pressure switch (OEM part number JTB000010).

I've been told that you don't have to degas the air con as its just unscrew the old switch and screw in the new one.

Can't find anything on the forum so is this true or an urban myth?

first-things-first · 11th March 2015, 20:05

I would expect an answer from those in the know. But, from previous experience with the same fault in a similar age FIAT. Yes, it was take out old and replace. Did lose a little probably as valve hissed when removed.

Sorry can't help with these cars.

bl52krz · 12th March 2015, 20:16

Best person to ask is Jules on here

SD1too · 12th March 2015, 20:42

Quote:

Originally Posted by IGH

A fault on the air con has been traced to the tri pressure switch (OEM part number JTB000010).

Hello Ian,

We deal with a lot of air conditioning faults on this forum and there has never been a fault with the trinary switch. I therefore suspect that you have been given a misdiagnosis. Who told you this, and what was their reasoning? Actually, it might be easier if you tell us what is wrong with your air conditioning and we'll take it from there.

Simon

IGH · 13th March 2015, 10:34

Thanks for you help with this.

The car is under a 3 month warranty from the car dealer who sold it to me, their fitter is ex MG Rover main dealer.

Can't fault the service as they fitted new cam belts (to a V6!!!), a new chrome trim on the front wing and carried out a service and MOT as part of the pre sale preparation.

They don't 'do' aircon (farming that out to a mobile independent). I thought, as the car is on a 53 plate and has only done 26,000 miles, that I get the amount of gas in the system checked by my usual garage (who I've dealt with for years) apparently the gas was at around 300 and they topped it up to the required level.

Whilst checking the system they spotted that the compressor clutch was not cutting in although the fan was 'clicking'(?) and it might possibly be a fault at the pressure switch, but it would need further investigation. They didn't charge me for the work.

Took it back to the dealer to be checked out and they came up with the diagnosis below.

As its under a 3 month warranty the work isn't going to cost me anything but I'd like to have an idea of what the options are if swapping the switch doesn't work, as I believe anything to do with the compressor clutch starts to get pricey!

SD1too · 13th March 2015, 11:21

Quote:

Originally Posted by IGH

... apparently the gas was at around 300 and they topped it up to the required level. Whilst checking the system they spotted that the compressor clutch was not cutting in although the fan was 'clicking'(?)

Ian,

Having extracted 300g of refrigerant I hope that they maintained a vacuum for at least 35 minutes to purge your drier of moisture. If not, you might have very high pressures (I saw this with my own car) and the trinary switch would then disable the compressor. The click is curious because a fan relay would be too quiet to hear with the engine running. The fan should be spinning anyway when the air con. is selected.

From what you say, they are not confident in what they're doing. I would find a mobile practitioner to come to your house and re-check the refrigerant charge and remove the stored moisture as I've described.

Simon

IGH · 13th March 2015, 16:40

Many thanks for the advice. I'll keep you posted on the progress!

SD1too · 13th March 2015, 18:13

Ian; I've just remembered that Reader Air are in your area. I have no experience of them, but they would be worth an exploratory phone call.

Simon

IGH · 14th March 2015, 16:50

Thanks for thinking of me. I'll have a look!

IGH · 29th March 2015, 17:11

Thought I'd give a quick update on the air con 'problem' on the car.

The garage that supplied the car came up with the same diagnosis as my usual garage (i.e. it might be worth trying a new trinary switch first).

The part took a week to arrive, from where I have no idea as they are as rare as hens teeth according to my research. It was an OEM part in a Rover box.

Popped in to have it fitted which should only have taken a few minutes to swap old for new and that's were the fun started.

It would not unscrew from the pipe. The fitter really, really had to struggle to take out the old switch.

I left him to it and popped into the office and when I got back the job was done but he told me that there was no gas in the system (this was interesting bearing in mind it had been charged up previously and the only fault found was the compressor clutch not cutting in).

Popped back to my usual garage the next day and an hour later went to see how they were doing only to be told they could not get the system to hold any pressure which pointed to a leak somewhere.

The mechanic and I on looking at the pipe that holds the trinary switch noticed that the pipe had a bend in it near the securing bracket holding the pipe to the body (just before the trinary switch). Not sure if the pipe had said bend before although looking at the pipe run couldn't see any reason for one to be there.

Being cynical by nature and bearing in mind the direction of the load/effort applied when the switch was being unscrewed did the fitter, when taking out the old switch, manage to bend the pipe thereby causing a leak!

Net result, straight back to supplying garage and the car is going in next week (with loan car supplied) and staying there till the leak, the compressor clutch not cutting in (together with the ICE controls on the steering wheel, the only other fault) are all sorted!

11th March 2015, 20:02	#1
IGH Avid contributor Rover 75 Saloon Join Date: Jan 2015 Location: Guildford Posts: 188 Thanks: 129 Thanked 48 Times in 21 Posts	Air Con Pressure Switch A fault on the air con has been traced to the tri pressure switch (OEM part number JTB000010). I've been told that you don't have to degas the air con as its just unscrew the old switch and screw in the new one. Can't find anything on the forum so is this true or an urban myth?

12th March 2015, 20:16	#3
bl52krz This is my second home Rover 75 cdt club + Rover 2.5 KV6 Conni SE Join Date: May 2008 Location: Birmingham Posts: 11,444 Thanks: 6,587 Thanked 2,262 Times in 1,729 Posts	Best person to ask is Jules on here __________________ Great Barr, Birmingham.

13th March 2015, 10:34	#5
IGH Avid contributor Rover 75 Saloon Join Date: Jan 2015 Location: Guildford Posts: 188 Thanks: 129 Thanked 48 Times in 21 Posts	Thanks for you help with this. The car is under a 3 month warranty from the car dealer who sold it to me, their fitter is ex MG Rover main dealer. Can't fault the service as they fitted new cam belts (to a V6!!!), a new chrome trim on the front wing and carried out a service and MOT as part of the pre sale preparation. They don't 'do' aircon (farming that out to a mobile independent). I thought, as the car is on a 53 plate and has only done 26,000 miles, that I get the amount of gas in the system checked by my usual garage (who I've dealt with for years) apparently the gas was at around 300 and they topped it up to the required level. Whilst checking the system they spotted that the compressor clutch was not cutting in although the fan was 'clicking'(?) and it might possibly be a fault at the pressure switch, but it would need further investigation. They didn't charge me for the work. Took it back to the dealer to be checked out and they came up with the diagnosis below. As its under a 3 month warranty the work isn't going to cost me anything but I'd like to have an idea of what the options are if swapping the switch doesn't work, as I believe anything to do with the compressor clutch starts to get pricey! Last edited by IGH; 13th March 2015 at 10:37..

13th March 2015, 18:13	#8
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: 20,630 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	Ian; I've just remembered that Reader Air are in your area. I have no experience of them, but they would be worth an exploratory phone call. Simon __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.

29th March 2015, 17:11	#10
IGH Avid contributor Rover 75 Saloon Join Date: Jan 2015 Location: Guildford Posts: 188 Thanks: 129 Thanked 48 Times in 21 Posts	Thought I'd give a quick update on the air con 'problem' on the car. The garage that supplied the car came up with the same diagnosis as my usual garage (i.e. it might be worth trying a new trinary switch first). The part took a week to arrive, from where I have no idea as they are as rare as hens teeth according to my research. It was an OEM part in a Rover box. Popped in to have it fitted which should only have taken a few minutes to swap old for new and that's were the fun started. It would not unscrew from the pipe. The fitter really, really had to struggle to take out the old switch. I left him to it and popped into the office and when I got back the job was done but he told me that there was no gas in the system (this was interesting bearing in mind it had been charged up previously and the only fault found was the compressor clutch not cutting in). Popped back to my usual garage the next day and an hour later went to see how they were doing only to be told they could not get the system to hold any pressure which pointed to a leak somewhere. The mechanic and I on looking at the pipe that holds the trinary switch noticed that the pipe had a bend in it near the securing bracket holding the pipe to the body (just before the trinary switch). Not sure if the pipe had said bend before although looking at the pipe run couldn't see any reason for one to be there. Being cynical by nature and bearing in mind the direction of the load/effort applied when the switch was being unscrewed did the fitter, when taking out the old switch, manage to bend the pipe thereby causing a leak! Net result, straight back to supplying garage and the car is going in next week (with loan car supplied) and staying there till the leak, the compressor clutch not cutting in (together with the ICE controls on the steering wheel, the only other fault) are all sorted! Last edited by IGH; 29th March 2015 at 17:17..

11th March 2015, 20:05	#2
first-things-first Posted a thing or two MG ZT Join Date: Jul 2014 Location: Hornchurch Posts: 1,255 Thanks: 176 Thanked 352 Times in 272 Posts	I would expect an answer from those in the know. But, from previous experience with the same fault in a similar age FIAT. Yes, it was take out old and replace. Did lose a little probably as valve hissed when removed. Sorry can't help with these cars.

13th March 2015, 16:40	#7
IGH Avid contributor Rover 75 Saloon Join Date: Jan 2015 Location: Guildford Posts: 188 Thanks: 129 Thanked 48 Times in 21 Posts	Many thanks for the advice. I'll keep you posted on the progress!

14th March 2015, 16:50	#9
IGH Avid contributor Rover 75 Saloon Join Date: Jan 2015 Location: Guildford Posts: 188 Thanks: 129 Thanked 48 Times in 21 Posts	Thanks for thinking of me. I'll have a look!