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a/c help-it's freakin hot out!

spyysee

Well-known member
Joined
Jun 15, 2002
Messages
124
Location
NY LI Metro
Corvette
1987 black beauty, all ez mods, owned '62,'78
Hey guys'
need a little help here,...mayby!!!!
The compresseor clutch will not engage when I turn on the a/c.
Been having problems(fast cycle on/off) and now the clutch will
not engage at all.
No voltage to the clutch plug(.33).
The pressure to the "can" reads 15lbs.

Any Thoughts??? C'mon guys, tell me I can get away with my
pants on.
I'm getting RIPE in the cockpit!!!!!
 

spyysee

Well-known member
Joined
Jun 15, 2002
Messages
124
Location
NY LI Metro
Corvette
1987 black beauty, all ez mods, owned '62,'78
C'monnnnnnnnnnnnnnn. I know we could do better than that.
 
S

Shadowing1985v

Guest
hehe, sorry

i never had air conditining problems, hehe
u said u arn't getting any juice right
thats kinda wierd
does it use juice from the bat or the alt

does anyone know? maybe a fuse. hehe
air conditionerings are like 70k miles rated
maybe something is just wrong with it
 

Paul G

Well-known member
Joined
Aug 27, 2001
Messages
200
Location
Griffith, IN, USA
Corvette
96 CE LT4 Convertible
I think you need a recharge. That pressure is too low. The pressure switches will disable the compressor clutch when the system gets low on gas. You say it used to cycle on and off. Then not even do that. Sounds like a low gas charge.
 
S

Shadowing1985v

Guest
wait, where is my mind

he is right your system is low on freon or how ever u spell that stuff


i had the same problem, i remember now... my pump was going on and off really fast. i thought it was my pump going out and then i charged it up and it stoped and it worked again
 

spyysee

Well-known member
Joined
Jun 15, 2002
Messages
124
Location
NY LI Metro
Corvette
1987 black beauty, all ez mods, owned '62,'78
Seems to be the consensus here.
thanx
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
quick way to test.

unplug the low pressure switch and hot wire it to itself (make a loop with a small piece of wire so it closes the circuit). Turn the key on and turn the a/c on and see if the clutch snaps in place. If so, you are either way low on freon, or the low pressure switch has gone bad.

Either way, you will need to put pressure gauges on it.

If it is a slow leak, it is often just as "cheap" to have a local shop simply top off the R12 vs. the time, expense, and hassle of going to R134. I do all my own a/c stuff anyway, but would be hard pressed for a full on swap if it is only about a lb or 1/2 lb low or so on the R12 stuff.
 

spyysee

Well-known member
Joined
Jun 15, 2002
Messages
124
Location
NY LI Metro
Corvette
1987 black beauty, all ez mods, owned '62,'78
service manual diagnostics

The GM service manual(1987 corvette) refers to a diagnostic computer test for the electronic a/c by holding down the rear defrost button and pressing the manual "up " button.
Well IT DOESN'T FREAKING WORK!!!

Which is the low pressure switch?
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
15lbs with the system off?

The Cold side ( Big hose )

should be around 40 is LBS when running

15 isnt enough You are LOW on charge!

I do not look @ precise pressures but tempratures the AC gauges are calibrated BOTH ways.

The suction side will be around 34-37 degrees ( which I believe is around 40 ish lbs... depending on they type of freon used)


Vig!
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
So you have the auto climate control I guess? If so, at 15 psi, you are way too low. It should be around 90 I think with the system off, and drop to about 35 on the large hose side (low side) when it is pumping down.

You have a leak there somewhere. You might consider the full 134 conversion. Get a new drier, O-rings, and orphis tube. It is a difficult thing for a do it yourselfer to do however if you don't have access to a vacuum pump to pull a vacuum on the system before refilling.

Check around you local a/c shops and compare prices for a full system over haul.
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Temp's & Pressures

35 degree discharge air is 32 psi pressure.

If the LOW side is under 20 ish...it will not kick on.

Static charge ( Assuming R-12 & 80 degree ambient temp.. full load of freon) will be 90 psi.


There you have it.


Vig!
 

Redbob

Well-known member
Joined
Dec 5, 2001
Messages
239
Location
Cross Roads, Texas, U.S.
Corvette
'89 dk red coupe
It's clear you've got a freon leak; there are substitutes out there if you can't lay your hands on any R-12 ( like the 3 cases I have set aside!), and that'd be far cheaper if all you have is say a bad 'O'-ring or leaky hose.
If you had to replace major hardware, well, the hardware is the same, R-12 or R-134a, and the R-134a will not perform as well with an evaporator and condensor designed for R-12, so I'd still say, stick with the R-12.
IFF you need to replace the compressor (which it does NOT sound like in this case) then I'd consider the R-134a conversion - along with all new hoses as well.
One trick a friend taught me is using leftover R-22 (see your home A/C guy) to find the leak, then using the precious R-12 for the final fill after removing all R-22. The R-22 at least is compatible with your compressor's current oil.
 

Paul G

Well-known member
Joined
Aug 27, 2001
Messages
200
Location
Griffith, IN, USA
Corvette
96 CE LT4 Convertible
If any one following this thread has used the HC12 I think it is called, how does it perform? It is supposed to be an R12 direct replacement. I saw it advertised but wonder if it is any good.
 

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