Couple of charging questions

[Jason94sport]

I had the system vacuumed & leak tested. The shop said it was good, no leaks. So they charge it. I gave them the 36oz spec per the Napa guide. About half way through they tell me the high pressure was a little high with no air movement around the condensor. Once they put a water hose on it the pressure went back down. Is this normal?

Second thing is the air is cool, but not really cold. The vent temp said 47 degrees. This is with max AC on. This seems high. They said they did not want to put anymore then 36oz in, but I suggested I'd consult some experts & get back to them. I can return & they will put some more in if it's needed.

I added the 7oz of oil before hand, replaced everything but the evaporator.

Should I just put a tad more freon in?

Thanks

 

[shamaal]

I had the system vacuumed & leak tested. The shop said it was good, no leaks. So they charge it. I gave them the 36oz spec per the Napa guide. About half way through they tell me the high pressure was a little high with no air movement around the condensor. Once they put a water hose on it the pressure went back down. Is this normal?

My Haynes says 28oz of R134a. But I'm suspicious of their numbers during the R12/134a crossover years. The A/C on these cars is simple and is designed for best performance when air is going across the condensor removing heat. Wetting it provides a similar effect. Yes it's normal for the pressure to drop when heat is removed from condensor.

Second thing is the air is cool, but not really cold. The vent temp said 47 degrees. This is with max AC on. This seems high. They said they did not want to put anymore then 36oz in, but I suggested I'd consult some experts & get back to them. I can return & they will put some more in if it's needed.

Personally I'm happy with anything in the 40s, but then I'm using a R12/134a convert. 36oz seems high to me but I don't have a 94. Sometimes it's on the EPA sticker next to the hood latch. Let's see if someone has a better spec for the amount of R134a refrigerant.

 

[Jason94sport]

The napa guide says 36oz. My 94 factory service manual says 26oz.

 

[CDW6212R]

The label on the radiator support should list the freon volume, it's very little in the late model systems. If it isn't leaking out and is filled to the proper level, and not cold, I'd have them do it again. Pull it back out, and refill it when the vacuum is pulled down completely. Good luck,

 

[shamaal]

Another approach would be to bring it down to 26 oz, let it settle for 5 minutes, then add refrigerant 2 oz at a time, let settle for 5 minutes and monitoring the vent temps. Once the vent temp starts to rise, dump 1 to 2 oz and you are set.

There's also a trick where you feel the evaporator input and outout lines, when they are within 3 degrees of each other you're set. This requires calibrated hands however.

Good Luck!

 

[Jason94sport]

Cool! After the holiday I'll give these thing a shot.
Edit: There is nothing under the hood that says anything about freon.
thanks

 

[gsmaclean]

Cool! After the holiday I'll give these thing a shot.
Edit: There is nothing under the hood that says anything about freon.
thanks

The label in my 94 that specifies the refrigerant type and amount is right at the back of the engine bay, next to the receiver/drier, NOT at the hood latch.

 

[gsmaclean]

The label in my 94 that specifies the refrigerant type and amount is right at the back of the engine bay, next to the receiver/drier, NOT at the hood latch.

Oh, and my 94 takes 36 oz.

 

[Jason94sport]

Ah ok thanks. Found it. It says 1lb 8oz of 134(24oz) & 7oz of oil. I got the oil in there, but I guess it's over charged now. I hate ford! Their own 94 service manual, & the PC at the ford dealer says 26. 2 different AC reference tools say 36. The label says 24.

So I'll have the system discharged & refilled to 24 & go from there.

 

[shamaal]

Sounds like a plan!

It looks like the automakers experimented with difeering systems during the R12/134a crossover years. I read somewhere that the components differed (different volume) on the A/C systems, but this is the first I've heard in the same year. It's good you found the EPA sticker, I'll update the database.

 

[CDW6212R]

Ford is very bad about changing mid year, and they also change their recommendations often.

 

[ma96782]

My 1994 Explorer sticker (located on the foil covering over the plastic evaporator housing) says....

R134a....1 lb 8 oz MAXIMUM

and 7 oz oil MAXIMUM.

Aloha, Mark

 

[Jason94sport]

Yep that's what mine says.

But I wonder......That's for stock 94 components. I have all new up to date components. Even lines. I wonder what effect(if any) that has.

 

[CDW6212R]

None, the internal volume of the compressor, evaporator and condensor are most of that spec.

 

[Jason94sport]

All is good now. Evacuated it. Put in 24 oz & it's nice & cold.

 

[shamaal]

Woo Hoo!

Another satisfied forum customer!

Thanks for the feed back.

 

[Glacier991]

Remember this rule of thumb... R-134 charge should be about 70% of an R-12 charge. In a system designed for 36 oz of R-12, you would only need 25 oz of R-134. Some 94 systems were R-12 and some R-134 as I recall. That explains the differences.

ps. In defense of FORD the changeover was EPA mandated and there was thought it might be extended (it wasn't). Lots of changes mid year that the manual makers did not catch up with.

 

[shamaal]

Rant On

You just touched on a pet peeve. I have no problem of course with Ford mixing and matching, there's usually a sticker somewhere with correct values.. I'm extremely annoyed with manual vendors who put out manuals with false information. The Haynes in question has a publishing date of 2000. The exact numbers were known and Haynes did not bother to update. It wouldn't be that difficult to put errata on their web page.

Rant off