Hey guys!

I'm back yet again.


I just wanted to post a update to thank everyone for helping me with my ac troubles. Sadly i did not get around to putting in the evaporator core (yet) however, this weekend i did a experiment and went to a different mechanic (which has very high reviews). I told him that my other mechanic told me that i had a huge leak in my evaporator core and that i must have it replaced. But the second mechanic i took it to told me he found NO leaks! He put dye in the system pumped the refrigerant and did couple other tests. It still blows cool air but makes that (hissing sound) that i talking about in my first post awhile back.
Do you guys think that sound is the compressor or maybe the vacuum line? Or something else maybe?

 

Hey rolex ,
I got a shot for you , this red marked area is what they changed at the last inspection after evap replacement . I hate to monger bad news but you will have to refill your gas again no later than 1 month because hissing sound you described suggests me your A/C is not done yet

 

Hi Mike,

I think the first thing is to settle whether the hissing sound is a vacuum sound or the sound of refrigerant through the expansion valve. The best way I know to indicate is to eliminate one of them and see if the sound goes away.
When the noise is present, open the bonnet and find the relay at the RH firewall that has a green base. Unplug that relay and it will stop the compressor, but not affect the climate control vacuum system. If the noise tapers off and goes away, it's the refrigerant you hear. If it doesn't change, then you have a vacuum system leak that you have to chase down.

Good luck.

 

Thanks for the reply guys,

I am taking it back to my repair guy later this week. What i think is happening is the condensation drains are clogged and its so backed up that the water is flooding the evaporator core. I try to unplug the relay to the compressor and see if the noise stops. thanks again!

 

Okay Steve,

I disconnected the relay with the green bottom and sure enough the sound went away Next step? lol

 

Well, two options. But first, you should settle on whether the A/C performance is up to snuf or not. If it cools properly, you have to decide if you can live with the hiss noise or not. If it gets under your skin, about the only thing you can do is replace the expansion valve. However, in my experience, replacing the valve is about 85% successful in curbing the hiss. Most folks that have presented a car with this noise have left it alone, but a few didn't like it and went for the expansion valve.

To cut to the chase, replacement may stop it, but there is a risk that it won't, or will only show a minor improvement. In any case, I'd suggest at least recovering the refrigerant and removing the valve, and checking it really close for any evidence of desiccant material inside. If there is any, that will mean replacement of the receiver/dryer as well, then charging her back up.

Ball's in your court, how big an issue is it to you??

Cheers,

 

Thanks for the quick reply Steve,

The A/C is blowing cool air, not cold like it should be so i am going to take it back to my repair guy this Friday and he is going to flush out the condensation hoses (which i really think are clogged because it gets really humid in the car and the vents sometimes blow out a small amount of water) and i will also have him check the expansion valve. thanks again for your help.

 

OK, I misunderstood, I thought it was cooling properly but hissing and misting from the vents. Now I suspect the expansion valve to be restricted, plugged, whatever you want to call it. That would be the cause of the hiss and weak cooling. Remember, if there is anything visible in the expansion valve, replace the receiver/drier, too. Actually, given the age, if it isn't really expensive, I'd replace it anyway if it was mine.
Have your guy be careful in cleaning out the evaporator case drains. You can't just ram something up the two outlets, there is a metal plate above that is there as a baffle. Just use air pressure and be prepared to clean them out every year. If you don't notice the puddle under the car every time the air conditioning is used, they are plugged up.

Good luck!

 

Ah, i should have explained it better. I got in the car this afternoon the noiced that the hissing sound stopped, but the air coming out of the vents is still just cool air. Could the expansion valve just stop hissing like that? O, well.

 

Yes, actually it can come and go. Many times cooler ambient temps can lessen it, and movement of any trash plugging it up inside can cause it to change.

Cheers,

 

Okay,

Sorry for the late reply to everyone(if anyone) that was following this. Last Friday after talking to my repair guy we concluded that the problem must be with the evaporator. The two pounds of refrigerant i had put in the week before was all gone! O well, it was worth the second try Thanks again for your help Steve.

 

Sorry to sort of thready hijack bu I have a similar issue.

My a.c blows cool but not cool enough and is sometimes intermitent on how well it does (Better on the highway). A mix of not much blower strength and not cool air makes it a bit over par.

I think part of the reason is a failed thermal switch not turning on the Aux fan ever and too much oil in the system(added by me being stupid and buying the recharge can with oil). My retrofit sheet says it has 3 pounds of 134a and 135ml of ester oil. I am sure I have too much oil at this point(far restricting my cooling capacity).

I know I can't get all of the oil out. Would the best bet to be to drain oil out untill I have taken out about what I have put in?

I plan to replace the filter/drier, would it be wise to replace the expansion valve as well? I have manifold and vacume pump to do the job as we;; as prior a/c exp.

 

Not using it could be the cause of the problem due a lack of the AC system lubrication. It pays to run the aircon system at least monthly.

 

Oh, no worries

I am getting my evaporator replaced next week at a jaguar dealer, believe it or not but the dealer is soooo much cheaper then both of my mechanics. Did you put the new dryer in yet?

 

another super helpful a/c guide you guys are awesome and im glad im a member here. btw anybody know the psi for xj6 r-12? im recharging tomorrow and cant find the numbers anywhere

 

We're always glad when someone finds us useful!

80 deg. F ambient temp, set on Normal, [not recirculate] idling:

Low blower speed
28-35 psi Low Side -- 180-220 psi High Side

High Blower speed
35-40 psi Low Side -- 200-250 psi High Side

Those would be average pressures for a system with a good receiver-dryer and no moisture in the system.

Hope the helps!

 

funny thing happened with that actually. i went to go get the r12 from a guy and he noticed there was a an adapter fitting. it was converted to 134a at some point so i just pumped it with 10 dollars worth of standard refrigerant and it was cold, no leaks. a/c blower crapped out finally tho it was shaking pretty bad for months and it finally gave out while pumping the refrigerant into it on high setting. so now i got a cold a/c but no blower to get it into the cabin. hilarious. one more question- low side valve is at the firewall or radiator?