92 Cont A/C Clutch Intermitent Engage

[Lankin]

Hello,
92 Cont,I just changed the high pressure hose that has the manifold on it by the compresser.I vacuumed the system down and charged it back up.All was working fine.As a matter of fact,it got down to 39deg.As soon I pulled it out of the shop,started cruising down the road,it stops blowing cold,doesnt blow hot,just not cold.I brought it back in a took another look.For the lif of me I couldnt figure it out.The pressures are still showing good.Switch was jumped,no leaks,just didnt have power to the compresser.
Now I get home pull into the drive,figured I would try it one more time,now the damn thing cycles when it wants to.Not a normal low freon cycle,just whenever.It never stays engaged longer than about 60 sec.I tried to get a code from the control head,but got nothing.Something is telling the clutch to disengage I guess.I am unesperienced with these beasts.Does a bad blend door tell the clutch to disengage?(I have read about blend doors.)
I even tried disonnecting the TPS sensor,the cooling temp sensor,hoping maybe one of them gave the computer a bad reading,still nothing.
Sorry so long,I am getting shoulder surgery Mon and am trying to get this going before I am down for a while.
Thanks for any and all help.

[Bluegrass]

You still have a system problem.
What did you recharge with? R12 or R134 what pressures do you see on the low and high sides?

[Lankin]

Thanks for the fast response.
Charged with 134.
Dont remember the numbers when the system was working properly.But my ac guy assured me they where good.
When clutch was not engaging,I cant be sure either.He said they were good though.i may take it back tomm.What should they show on both sides under both conditions?He didnt say there was a leak when I brought it back the second time.I saw the gauges and there was still pressure in the lines,but cant remember the numbers.
I am in the Military and am using our on-base Hobby Shop to do all the work.

[Bluegrass]

According to my retrofit charts, your car still had an Freon R12 system.
There are specific system changes to be done to retrofit to R134.
What has been done?
The system can't be refilled with 134 and be expected to work as usual without doing the minunim changes.
134 fill weight is usually less than 12 to begin with.
The system vaccuum check should hold for at least 15 minutes or more for 134 use because 134 has a smaller molecular structure and will find a leak faster than 12.
What do we have?

[Lankin]

The car was bought used and without a/c working.It is a factory R-12 system but was changed over before me so I am unsure what was done.What was supposed to be done.Looks like a new drier/accumulater,but then again the whole car is in good shape,so it may not be new.I remember him saying where not going to use the amount on the underhood sticker,we put less in,be me reading your post,looks like u mean we need to put more in.It did hold a vacuum for more than 15 min.It was on 29 if I remember right,and he said it was good.It held it for about 20 min after we shut it off.This is one of those 5k dollar machines.Brand new.So I wasnt to into,getting my hands to involved,afraid of breaking something.
Forgot to mention,we let it idle in the shop for about 25 min after we first charged it.Checked the gauges one more time,then disconnected.It still worked fine.Until Igave her some gas going down the road.Hasnt been right since.

[Bluegrass]

Vacuum check is fine. If he took out the gas that was there ( to change the hose) and it was 134, the fittings used would indicate which gas was in the system.
My guess is there may need to be additional 134 introduced.
Low charge is usually what makes the compressor cycle excessivley if there are not other problems.
Conversion to 134 from a 12 system to be more complete would include a larger condenser as well as changing the dryer and orfice and possibly resetting the pressure switch cycle timing.
Your servicer should be up with all this unless it's a shop like Jiffy Lube that dosn't deal with retrofits normally.
Let us know how it turns out.

[ekooke]

Did you check the WOT switch (if 92 models have them)? I keyed on this because you said it worked fine "Until Igave her some gas going down the road". The WOT (wide open throttle) is a switch that disengages the compressor clutch power for temporary additional passing power.

[Icarus]

Maybe check the air gap between the pulley and hub as well...

FX-15 compressor : 0.018-0.033"

Make sure the cutch cycling switch contact is good and clean as it can cause an erratic cycling too...
Whats the temp/humidity outside like there?

[Icarus]

ps: the clutch shouldn't stay on for more than ~60 seconds unless the temp is above ~78-80*F...

[ekooke]

quote:Originally posted by Icarus:
ps: the clutch shouldn't stay on for more than ~60 seconds unless the temp is above ~78-80*F...

That's quite true. Even if the clutch were cycling 2~3 times a minute, it should still be blowing reasonably cold air inside the car. It may be too much oil in the refrigerant that's causing cooling inefficiency, the EATC control itself, blocked orifice tube, gummed-up accumulator, frozen evaporator, low refrigerant charge, or lack of enough airflow on the condenser.

[Lankin]

Well,
Here is what I learned.The clutch seemed to be cycling because of low refrigerant.There is a slow leak on the low side.Other than that,the clutch is worn out and doesnt always engage when told to.If you bump it with a bar it engages no problem.Another words,the clutch plate is worn out.To much clearance for the field to pull it in.
So I am off looking for a new comprsessor.It will have to wait a while before I put it in as I cannot do it with one arm!(See above)

[ November 02, 2003: Message edited by: Lankin ]