The high pressure A/C valve on my XK8 is leaking. It is not the usual schrader type valve. Rather, it looks like a small, black plastic round ball valve. Is this normal? If so, can you replace it with a schrader type valve?

 

As soon as I take the plastic cover cap off of the high pressure valve there is a hiss of escaping air. The low pressure valve when removed there is no hiss. My understanding is these are merely dust caps and are not suppose to prevent freon from escaping, the valve itself is suppose to do this. On the other hand, this valve is not a schrader valve but a type I am unfamiliar with, so I am not sure what is 'normal'.

 

Also, how do you know if you need to add oil to the A/C system or not? I know that both too much and too little can damage the system.

 

It is the same valve as on my 98, and it shouldn't be leaking. I don't think that it is a serviceable part.

If it's not been replaced for a long time it's simpler just to replace the receiver/dryer (not hideously expensive) and get a system evac/recharge done. Do get it professionally drained as R134 isn't particularly environmentally friendly, and there could still be a lot of pressure left.

I've just replaced the condenser & dryer on mine. I mentioned oil to the tech who did the evac/recharge and he said he would add some depending on how much refrigerant was extracted? Presume that is OK as it's been blowing super-cool since the job was done.

HTH,
Mike

 

So, a non-schrader valve is the correct fitting? Do you need some kind of adapter to re-charge the system using standard charging gear?
As far as pressure, I have almost none. The system is not blowing cold at all. So, its been leaking a long time.

 

Remove (recover) refrigerant from the system, unscrew the service valve.

Take the old valve to a well stocked auto supply store and match the valve. Ford uses these valves so it is not some strange part.

Install new valve, evacuate and recharge system.

I do this at least a few times a month in the Summer.

I buy the low and high side valves in boxes of 5. I go through many a year. Four Seasons or FJC brand valves are what I use.

The Jaguar Dealer can get them also.

bob

 

Do you have the part number for the high side service port? It sits right on top of the receiver. I have tried 3 local parts shop plus the local Jag dealer and no one has it. Yes, I took the actual part with me and no one could match it. Very frustrating. Below is a photo of the part:

 

Everyone wants to sell me a schrader valve because the book tells them that is right part, but this is a ball valve...... ball valve is not serviceable, so you have to replace the entire port.

 

Jaguar part # is MHD7372AA. Seems to be freely available.

 

The part in your picture is TWO PARTS!!!!!!!!!

The TOP part of the unit you have is the valve (that needs replacement). The bottom STEEL part is the adapter.
You need to SEPARATE the top aluminum part from the STEEL lower part and install the service valve back onto the steel lower part.

You took the entire part off and you only need the top part that the refrigerant service hose connector attaches to.

You will need to use pliers or something to separate the valve from the adapter and be careful to not scar-up the new aluminum service valve when re-installing the part to the steel lower adapter.

bob

 

THANK YOU, THANK YOU, THANK YOU! I had the correct part, it is Santech MT2907. This gives you both the high and low pressure ports. I had no clue the lower part was an adapter. It was causing me no end of headaches! Thanks again!