Yes, that's it. The arm should move from about 4 o clock position to about 2 o clock as it goes from open to closed.

If your AC isn't cold, it could be that you're low on refrigerant.

 

In my case, it does go cold when it's properly on, but I wouldn't call it the "Siberian Winter" that several people here have said it should be. Certainly chilled beyond ambient and enough to keep me comfortable, mind.

 

I think I can get my vent temperatures to 3 degrees, so it's cold.

 

If it helps my system works well, except on cold, a bit of cold air blows on my feet, much less than it did before I found a disconnected vac hose, it used to turn my feet in to ice cubes.
So if you want some temp readings let me know. PO spent 4k in a dark room getting this system to work, why a dark room, no idea.
But if work great. I make sure to run it every couple of weeks... no drying of seals. Paranoid yes..Fingers cross yes... Pray yes...long live the cold air.
Oh and the system a new heater valve... LOL

 

 

3 to 5 is my aim point for all my cars. I don't want it below freezing, otherwise the moisture in the car can turn to ice in the evaporator and block the airflow, but I want it just above freezing. AC is a thing I'm fussy about, I want it to work well in all my cars, so I bought the tools to do it myself. I've saved thousands by doing it myself on various cars and friends cars over the years.

 

Hey guys I,m having the same issues its a few years later now, and i,m wondering if this issue was ever solved, I am running a chevy 350 with a clutch fan, when i start the car you can actually see the sweat on the a/c line going to the evap coil, evap temp is about 38 with fresh intake dampers closed on compartment circulation open, about min into it i cant get the temp below, 67, and no more sweating, New compressor, new dryer, new txv valve. i,m going to try the water on the condenser test tomorrow, my head pressure is around 200 but climes to 250 that tells me i,m having an issue with the condenser not moving enough air through it, I did the thermometer test across the condenser and its a steady 150-160 through 90% of the coil. Any help or input is appreciated .. P.S. my heater core is also bypassed. for no heat. just like the other Gentleman.
Thanks

 

As an update, after monkeying around with the heater valve, I suspect that’s been the problem as the air coming out of my AC has remained in the 40F degree range.

I will likely end up replacing the heater valve with the plastic counterpart. Four Season 74803. The actuating arm on the crummy pot metal part made it harder for the valve to work properly. After manually actuating it, it seems to be working fine now. It just looks like such a badly manufactured part....heavy, cumbersome to operate.

 

Four Seasons is generally regarded as crap in the heating and AC markets, so maybe not get one of those!

 

It's gotta be better than the crummy MTC branded heater valve I have in there now....

Stay away from anything branded MTC.

 

In the morning, when i drive to work, the AC gets down to 40F! Mind you, it’s 80F outside at this point. Sometimes super humid, sometimes not as much.

When I take the car home, sometimes it takes a while to get down to 50F. Like it’s struggling to catch up. It’ll blow 70F rather quickly, but then takes a long time to get down to 60F. It will eventually get there, and then into the 50s, but not like when I start it up in the morning.

Is there anything that can make the AC work like that?

 

What are the outside temperatures when you take the car home? Is your drive stop and go or freeway driving? Sounds like it's an airflow issue and is struggling to shed heat from the condenser.

 

That’s kind of in line with my AJ16, Vee. Once mine cools, it cools better than yours, I think, but after the car has been on, parked and driven, it takes a while to get there. If the car would be parked outside (which I avoid at all costs) it also takes a while to cool. Mine is more of a weekend car and if driven thru the weeks it’s more intentional driving. It never usually gets parked in the direct heat, or is driven thru heavy heavy traffic, so it has a chance to cool better. But it definitely keeps me comfortable in the 100 degree Texas heat once it cools down. If you know how much refrigerant is in there, I would avoid overcharging that system. I know in some quarters the answer is always that the system is undercharged. This is not true. If you have close to the factory recommended amount of refrigerant in there then it may be that you are used to how more modern cars cool or that you have some other weak link. Trust me, overcharging is not fun. Compressor locks down and you have to figure out a way to purge the system to get it going again

 

This is a 1978 car where he retrofitted a more modern parallel flow condenser and reported vent temps 5-6 degrees cooler than the original. He's in Florida, and seemed happy with the result. I don't know what type of condenser the late 6 cylinder cars have, but I'm sure a modern ( and clean!) condenser could help the cooling.

Installing Parallel Flow Condenser

 

JagBoi64, The condenser has been replaced in the last 5 years or so. (As well as the dryer) I don't know much about the parallel condenser. I replaced it with something that looked exactly the same as what I took out!

The drive home is mostly highway...its been hot here. I drive top down when it's anything less than too hot! The drive is ideal traffic, but it is 15 degrees hotter on the way home.

Spikepaga, perhaps its just the way it is. It's frightfully cold in the morning. 40F is freaking cold after about 10 minutes of driving. I can never seem to get there on the way home. It's parked in a garage at work. Stays generally cool.

 

I have a feeling your car may be working as intended. Maybe your aux electric fan is not operating or it’s weak?? When you leave the office on the drive home, do you immediately get into traffic or does the car have a chance to run for a bit? These cars need more time to cool than others in my experience.

For me, replacing the stock electric aux fan with a SPAL fan helps quite a bit. I suspect if I where to replace the main mechanical fan with an electric one, I would have even better results, but the draw is a concern and also the fact that a mechanical fan is always operative. If an electric fan goes out, it’s done.

But I emphasize again, do not overcharge your system. It’s the worst thing you can do.

 

Reading through this thread. I replaced the metal stamped heater valve with the Four Season valve. Mine had developed a small leak at the shaft and if you don't do routine coolant level checks on your 20+ year old Jag you may be up for an expensive surprise. I didn't what to pay a premium for a failed product and chose an reasonable alternative.The Four Seasons valve is cheap and can be replaced annually if you don't trust it. Toyota has used ABS plastic heater valves, cable and vac operated ones, for decades.

In addition: a vac pump would be handy to check the heater valve diaphragm. Another tool you need is an A/C gauge set if you want to troubleshoot your AC system. You need a chart that tells you were the pressure on the suction and pressure side of compressor should be at given current temperature and humidity. Another issue could be an overcharged system that freezes up your evaporator or a worn out A/C clutch where the gap is in access of spec.

 

Do You Happen to know if the climate control ECU from any other models will work on my 1989 XJS convertible

 

I don't think so. The XJ6's use an ECU that looks the same, but has different part numbers. The AC in the sedans has functions the XJS doesn't, so may not be compatible. I don't know if an XJ6 one would work if plugged into an XJS though.

 

I remember hearing all the way back to the early 1970's that if you change out the compressor, also add a new receiver/dryer.
My 96 XJS just turned 54,000 miles. But the last 4,000 miles took about 7 years. So many of the usual no-drive syndrom parts needed to be replaced. (my bad). Won't let this happen again. LOL
The front seal on the compressor was leaking, and so was the high side schrader valve. So had both those replaced along with a new receiver dryer. The heater valve was also leaking and had that replaced. The A/C now blows ice cold. And the heater works fine (for a British car LOL).

What I have noticed over the past 20 years is that it generally does not like very hot weather or long time stop and go traffic - especially both. When I take her out for a drive the temperature gauge stays right at the middle operating temp mark no matter how fast or slow I drive. The other day I was sitting in line waiting to get gas. So it was sitting at idle for easily 10+ minutes. I noticed the temperature guage start to move in the hot direction. Not the danger zone, but noticeably climbing to about half way there. So I shut the engine off. When a pump became available, just started her up, got gas and started her up again and drove home 2 miles. I wonder if this is just a normal quirk with the 4.0 (?)

Rick