I have an xj6 and I’m trying to fix the ac before it gets really hot outside
I have made sure the servo works by wiring directly to a battery and I get the whirr and can see it moving
The heater valve I have take care of by bypassing heatercore as I don’t have a heater valve
So what would be my next steps in getting the ac to work. I haven’t charged the system yet as I only have a little bit of freeze12 and I don’t wanna waste it. It says freeze12 on the evaporator I believe and the po gave it to me
Hello Jabraan - try to find a can of Leak Detector for the ac system, then use that to put in the system to check for leaks, prior to using your supply of the R12 - Tex Terry II 1991 XJS V12 Classic Coupe, 1986 XJS V12 Coupe - 3/1/2020 1936hrs. EST USA
Jabraan,
I have fully restored the Climate Control Systems in three of my older Jaguars, that operated without A/C for a year or more for a variety of reasons, including two Series III XJ6s. They were all originally designed to work with R12 and I got them all working properly again with R12.
As far as first steps are concerned, you need to make sure that your A/C system is leak free over a long period of time (days) before you try servicing it with anything. So the first step is to remove and replace ALL o-rings at the rear of the compressor, evaporator, condensor, fuel cooler, receiver drier, and expansion valve. Lubricate each o-ring with the proper oil for your planned refrigerant and tighten all fittings securely. Then connect a vacuum pump (I got mine at Harbor Freight) to the service fittings, evacuate the system, and verify that it will hold the vacuum without leaks over several days (I let the cars sit for a week without any noticesble drop in vacuum before feeling that it was leak free). The system should hold and maintain about 30 inches of mercury in vacuum for several days at a time. If it doesn’t then you need to find the leak. The usual source of leaks for me were the A/C compressors and hoses. After replacing the leaky components and verifying that the system is leak free, remove and replace the receiver drier with a new one, verify again that it is leak free, and try servicing it.
There are many other components to consider but the first step for me is to make sure the A/C system will hold a vacuum. Then the fun begins with the electrical components.
I found that getting the A/C systems to work properly again was very difficult, time consuming, and frustrating. However I was successful in three out of three tries and I greatly enjoyed driving around in air conditioned comfort in these cars once again.
Hello Jabraan - my suggestion to use the Leak Detector was provided on the assumption that you would have completed all the steps Paul mentions above - doing anything less may well be just a case of loss of time and money - Tex Terry II - 1991 XJS V12 Classic Coupe, 1986 XJS V12 Coupe - 3/1/2020 2110hrs. EST USA
You said that you checked the servo, but do you know if your AC Amplifier works as well?
On AC mode air should be coming only from the center vents.
Mind you that there are various, mechanical or electromagnetic, vacuum operating valves involved to open and close the vents so if any is at fault the system will not work as it should.
Make a thorough check and tell us the symptoms so we can help better.
If you have bypassed the AC Amplifier testing the servo is irrelevant… You should position the servo in the full cold position and see if the flaps are in their correct position.
Bypassing the amp might give you more problems than benefits, and the first will be that in full cold the system is always in recirculation mode.
You should at least have some manual control of the servo via some switces. You can do this your self, or look “Jag Air” for a ready solution.
**
The heater core is an essential part of temperature control, Jabraan - without it; the system will blow really cold at all times. Which admittedly allow cabin temps to be controlled by fan speeds or switching system on and off. However, if the servo operates; using that and/or a working AC amplifier - the heater core can be used to temper the cold evaporator air…
The system works by using flaps to bypass the heater core for full cold - or partially through the heater core to temper the air…
While a leak detector is useful for locating a leak, if any; a leak can only be fixed by emptying the system and repair the leaks. If the system is emptied; it is important to apply vacuum to the system to eliminate any water in the system, and to detect any other leaks. The receiver/drier is always replaced if the system is drained…
My cars amplifier wasn’t working so I’m gonna replace it with a switch. But before that I decided to see if everything works by putting power to the servo motor and it’s working and I hear the whirr so I can move it from hot to cold. But the air isn’t coming from the center vents
And I bypassed the heater valve because that’s basically what it does when on full cold mode and I don’t want any hot air seeping in my car because it gets really hot here in Texas
Jabraan,
You are trying to get your A/C system to work in a way that it was not intended to work and with some components missing or inoperative. I am not sure how much help I or others will be able to give answering your questions.
I’m only after cool air not hot air so if the cooling part of it was working I’d be happy. The only thing I haven’t done anything unusual considering the switch takes place of the amp and the valve does exactly what I’ve done when set to full cold
**
Operating the servo manually is perfectly feasible, Jabraan. The servo is the arms and legs of the system, where the AC amplifier is the brain - the switch just replaces the amplifier with a human…
The servo operates the various items using vacuum switches, mechanical pushrods and microswitches - cam operated. Set to full cold; vacuum is applied to the centre vents to open them, the water valve is closed by vacuum and pushrods reposition the heater flaps to bypass the heater core. In this situation; ‘bypassing’ the heater valve is pointless…
That the centre vents do not open implies either that the servo is not in ‘full cold’ - or the vacuum to these vents has failed. As vacuum is holding the defrost vents closed; with general loss of vacuum the defrost vents are always open.
Without vacuum the system will malfunction even if the servo operates normally - you need to verify that you have vacuum…
One other vacuum problem; in ‘full cold’ the recirculation flaps are set to ‘recirculate’ by vacuum - the vacuum hose to the recirculation flaps should be disconnected if you always want ‘full cold’
Which really is a bit belt and braces. Without the heater core use; the compressor engaged will always run the evaporator full cold - and resetting the servo will only alter the path of the air flow. Ambient air will influence the temperature of the air flow, but with low ambient temps the cabin air flow will be low indeed…
In short, with a fully functioning servo, manually controlled; use the heater core as originally intended - it will not compromise cooling…
Jabraan,
If your refrigerant pressure is only 20 PSI then I believe that you do have a leak.
When I got the A/C working again in my two former XJ6s and my 1990 V12 Vanden Plas I first made sure that they held 30 inches of vacuum for a week or more, then I took them to a local shop to have them professionally serviced with R12. I have never added the refrigerant myself so I am not sure exactly what the “yellow zone” you mentioned means.
When I got home from the A/C shop with my 1984 XJ6 Vanden Plas last year it had a fully functioning Climate Control System again with all heat and air conditioning features working exactly as designed. I was curious about what the pressures were inside the A/C system so I hooked up my A/C manifold set with hoses and high and low side gauges to the appropriate Schrader valves. With the engine off both the low and high gauges read about 75 PSI (much higher than your 20 PSI). With the engine running and Climate Control System on at full cooling the low side gauge read in the range of 22-26 PSI and the high side gauge side read in the range of about 150-180 PSI. Because the compressor clutch was being engaged and disengaged automatically by the A/C amplifier the pressures were constantly changing. At the time the interior air vents were putting out air temperatures in the range of about 40-45 F.
I believe that your system pressure of only 20 PSI means that you have a leak and that if you add any refrigerant it is very likely to leak.
I must mention that I am not an A/C professional, that I have had my R12 serviced only by licensed professionals, that I only have experience with R12 serviced A/C systems (not R134A) and that my observations were typical of the three Jaguars that I have owned and worked on myself.
Mr.Paul, I need your help, I have AC issue in my s3, and can’t find any information about it, so maybe you could give me some advice.
First I noticed that with AC on, my voltmeter start to get down to the red zone, next my RPM in idling went down from 800 to 580-600 (before it was from 800 to 700).
I thought that my alternator is dying, so I replaced it to 94 amp, but it didn’t help.
A few weeks later AC just stopped. All fuses are good and in general, ac worked well before it happened. I have checked and cleaned all grounds and made the jump from battery “-” to AC body.
Help me please, where should I look?
Andy,
Working on automobile air conditioning systems requires specialized tools and training as it can be dangerous. It sounds like your refrigerant might have gotten low and your A/C compressor froze up or your compressor failed for another reason (low refrigerant oil?). Does your A/C compressor have a Superheat Switch with a fuse or a High Side Low Pressure Switch at the rear? Do you have a manifold gauge set to check the refrigerant pressures on the high and low sides? If you do, what pressure is in the system now?
There is a lot of information about the Series III climate control system in the Jaguar Series III Service Manual. Do you have a copy of that important document? There are probably hundreds of posts related to inoperative A/C systems on Jag-Lovers. Have you searched the archives for helpful information?
I have turned to A/C professionals in the past and you should consider taking your car to an A/C professional or a local independent Jaguar repair shop or dealership if you have one nearby.
LnrB,
The A/C compressors in the climate control systems of the Series III saloons were equipped with Superheat switches or High Side Low Pressure (HSLP) Switches to prevent them from running when refrigerant was low. They should have protected the compressor unless those protective systems were not installed or disabled.
