I've got a question regarding the functioning of the compressor.
Does the compressor come on every time the A/C switch is turned on? My A/C
has never worked, so tonight while chasing around whirring sounds under my
car I thought I'd take a look. At first when I pushed the A/C button, the
center of the compressor pulley started spinning. When I turned of the A/C
button, the center still turned for a few minutes, and then stopped. When
I
pushed to button on again, the center of the pulley didn't spin. I shut
the
car down, restarted it, and turned on both front and rear A/C at full blast
and let the car run for a few minutes, and the center of the pulley never
started turning.
I would note that when the compressor was turning, I could see bubbles in
the sight glass. One last comment, someone mounted a Ford compressor on my
shark, and fabricated a rear bracket for it to fit.
Questions:
1) Is my compressor acting typically, or should it run any time I push the
A/C button?
2) Since I saw air bubbles in the sight glass, I'm assuming that I have no
(major) leaks in my system, correct?
3) Is there any way for a tech to tell if I have R-12 or R-134?
4) If I still have R-12, where can I top off, or do I have to convert?
5) Is my shark now considered a hybrid because I've got a blue oval
compressor?
-Adam Birnbaum
===================
Adam, here are a few answers:
1. No, your compressor is not acting normal. When you turn on the a/c,
the compressor should come on then turn off when the evaporator in your
dashboard is cool enough, then turn on again as the evaporator warms up
again--the compressor should cycle on and off every few minutes. This
will almost always mean that it turns on when you press the a/c button.
2. Good assumption, but only an assumption. If there were no leaks, you'd
still have all your refrigerant. If nobody has serviced the a/c for ten
years, you might be fine.
3. You can tell at a glance if you have been converted to R-134a: the
fittings must be changed to quick-disconnect fittings (similar to an air
tool hose, but smaller) with red and blue caps, and there should be a
sticker saying you've been converted--the sticker is included in the
conversion parts kits, but that doesn't mean it's always applied.
4. In the northern Virginia area, any shop that does a/c has R-12. I
converted my car myself, and I don't recommend that unless you're as
cheap as I am but it works.
5. I don't know. Counting nuts and bolts, I've got parts from Mercedes,
Porsche 944, Honda, Renault, JC Whitney, and others on my car.
Ray Wach
=====================
At 10:03 PM 6/6/00 -0700, ADAM BIRNBAUM wrote:
>Questions:
>1) Is my compressor acting typically, or should it run any time I push the A/C button?
The compressor clutch should engage as soon as you push the button. It
should then run as long as the A/C is on, EXCEPT that there is a "freeze
switch" that monitors the temp of the evaporator and turns the compressor
off when the evaporator temp goes below freezing. This keeps the evaporator
from icing up. There is also a pressure switch on the receiver/dryer that
will not let the clutch engage if there is no freon pressure in the system.
(The compressor depends upon the oil that circulates with the freon for
lubrication, so no freon means no lube, which ruins the compressor.)
If the compressor clutch doesn't engage, check the freon pressure. If that
is OK, the problem is often the A/C relay in the HVAC control head. There
is an excellent repair procedure (written by dr. bob) in the archives and
on Greg's Tips page.
>2) Since I saw air bubbles in the sight glass, I'm assuming that I have no (major) leaks in my system, correct?
Nope. There should be a stream of bubbles for about ten seconds when the
clutch first engages. The sight glass should then clear and stay clear. The
receiver/dryer is a can with mixed gas and liquid freon dribbling in from
the top. The outlet tube almost touches the bottom, so it should be pulling
pure liquid for the expansion valve. If you get bubbles while the system is
running, you are low on freon.
>3) Is there any way for a tech to tell if I have R-12 or R-134?
It is required that the service valves be changed from the standard 1/4"
flare to an acme thread when the system is converted. If you still have the
standard fittings, you should not have R-134a. EPA is rigid in the
enforcement of this. It is actually pretty difficult to do an "outlaw"
conversion without changing the fittings, because everything having to do
with R-134a uses the acme threads. If you have an outlaw conversion, it can
lead to serious cross-contamination of a shop's reclamation system and
their supply of reclaimed R-12 - not good!
>4) If I still have R-12, where can I top off, or do I have to convert?
You can still legally buy R-12 across the counter at most parts stores. You
have to become certified to do so, however. This is pretty quick and easy.
The only reason for certification is to ensure that you know that freon
should not be vented, but should be recycled, so the test is very, very
easy. You can get certified on the web.
>5) Is my shark now considered a hybrid because I've got a blue oval compressor?
Ford conversions are pretty rare. Charlie Griffith offers an aftermarket
compressor conversion kit for 928s.
Wally Plumley
928 Specialists
================
hey guys
I just went down to have my AC recharged. Very interesting. I hovered
around my car as the guy did the work to learn a few things on the AC
systems in general. had the car up high on a lift so it was nice to have a
good look see from underneath. I'm usually on my crawler with my nose
scraping the undersides...so this was a treat. Anyway.......
I'm not to sure of the guys ability's who was performing this work as the
conclusion is I NEED A NEW AC COMPRESSOR.
QUESTIONS/ OBSERVATIONS I HAVE....
1) Are there two service points on the 87s4 AC system ??..#1 port up front
near the sight gauge which the tech said was the HIGH PRESSURE SIDE and #2
port on top of the compressor itself the LOW PRESSURE SIDE (we found after a
phone call), the place where the freon is introduced?????????????????
2) which one do you pump/service the freon into??
He had tried port #1 to no avail because he said this must be the HP
side.. there must be a LP port somewhere?? At this point we didn't know #2 was
on top of the compressor. I hit the Speed dial on the cell to 928intl and
found out there is a port on top of the compressor as well...the tech said
this MUST be the LOW PRESSURE SIDE and this is where you service it. He
unhooked the hoses and tried it there. With the engine on and AC engaged
again he started the process. The problem lies in that the freon level/ his
gauge wasn't dropping in his tank? We checked all his connections by slowly
loosening them to see a bit of freon spray out....did this all the way to
the port on the compressor.
HE SAYS THE COMPRESSOR IS SHOT BECAUSE IT ISN'T SUCKING/DRAWING IN THE FREON
FROM THE TANK? Does this make sense?
Now to me, using my knowledge on weather...things flow from HIGH TO LOW
pressure. Even if the compressor was OFF.. shouldn't the HIGH PRESSURE FREON
in the tank flow into the LOW PRESSURE port on the compressor
even if it WASN'T running?
Does it really SUCK the freon out of the tank or around the system in the
car? To me the pressure in the tank should have dropped the minute he opened
the valve regardless of AC operation??
ANYWAY...with the AC engaged.......there are a few bubbles present in the
sight gauge...the clutch engages....there is a faint hissing from the
evaporator housing behind the center vent. These ALL tell me (the clueless
one on AC) that the compressor is perhaps indeed working and that the TECH
is #%#%ing up. I don't want to fork out $$$ for a compressor right now...at
least it is still window weather in Vegas.
3) is there a "safety" that has to be released on any of these ports
to be
able to allow freon to enter or escape? (besides the schrader valve)
Any tips.. pointers.. BTDT regarding AC service and what to look for would be
awesome.
Besides, with summer approaching us all. it could be useful to all of us
Thanks...ok.. I'm done now
Tony
==============
At 01:49 PM 3/20/01, you wrote:
>1) Are there two service points on the 87s4 AC system ??..#1 port up front near the sight gauge which the tech said was the HIGH PRESSURE SIDE and #2 port on top of the compressor itself the LOW PRESSURE SIDE(we found after a phone call), the place where the freon is introduced?????????????????
Yes. The high side is at the receiver/dryer.
The low side, where the freon is put in, is hidden on the large A/C line
between the radiator and the engine just under the coil on the passenger's
fender.
>2) which one do you pump/service the freon into??
Low side under the coil.
>He had tried port #1 to no avail because he said this must be the HP side.. there must be a LP port somewhere??
Uh-oh. This instantly tell me that he isn't an A/C expert. Anyone who knows
anything about A/C would know that the receiver/dryer, and that port, are
on the high side.
---
>At this point we didn't know #2 was on top of the compressor. I hit the speed dial on the cell to 928intl and found out there is a port on top of the compressor as well...the tech said this MUST be the LOW PRESSURE SIDE and this is where you service it. he unhooked the hoses and tried it
there.
---
He should have had one hose to the high side, one to the low side. If you
don't have the high side hose connected, you don't really know what the
system is doing. You need both hoses hooked up.
---
>With the engine on and AC engaged again he started the process. The problem lies in that the freon level/ his gauge wasn't dropping in his tank? We checked all his connections by slowly loosening them to see a bit of freon spray out....did this all the way to the port on the compressor.
HE SAYS THE COMPRESSOR IS SHOT BECAUSE IT ISN'T SUCKING/DRAWING IN THE FREON FROM THE TANK? Does this make sense?
---
Nope. Sounds like the port on the compressor is a service port with a valve
that must be opened, or his hose fitting didn't have the little tab to
depress the schrader valve in the compressor port, or ??
----
>Now to me, using my knowledge on weather...things flow from HIGH TO LOW pressure. Even if the compressor was OFF.. shouldn't the HIGH PRESSURE FREON in the tank flow into the LOW PRESSURE port on the compressor even if it WASN'T running?
----
Yep. In fact, if you start with an empty system, you can let liquid freon
flow into the system from the tank.
Remember that the high side/low side pressures will be the same unless the
compressor is operating. You normally charge the system with the compressor
running.
This is a good time to point out again that if you compressor operates, the
system ISN'T empty. The compressor won't run if the system is empty unless
you disconnect and jumper the freon pressure switch harness.
----
>Does it really SUCK the freon out of the tank or around the system in the car? To me the pressure in the tank should have dropped the minute he opened the valve regardless of AC operation??
---
It might not have dropped much if any. One of the characteristics of freon
is that if you have both liquid and vapor in a closed system, if you know
the temperature, you know the pressure. In other words, if the compressor
isn't running, and you have an ambient temp of 70 deg F, you will have 70.2
psig in both your car and his tank. If the car is warm from running
recently, the pressure in the car is going to be higher.
---
>ANYWAY...with the AC engaged.......there are a few bubbles present in the sight gauge...the clutch engages....there is a faint hissing from the evaporator housing behind the center vent. These ALL tell me (the clueless one on AC) that the compressor is perhaps indeed working and that the TECH is #%#%ing up.
----
Right.
>I don't want to fork out $$$ for a compressor right now...at least it is still window weather in Vegas.
You don't need a compressor. You need to learn how to work on your A/C.
----
>3) is there a "safety" that has to be released on any of these
ports to be able to allow freon to enter or escape? (besides the schrader valve) Sometimes, but not usually on car A/C units. The house system has service valves that have to be opened.
Any tips.. pointers.. BTDT regarding AC service and what to look for would be awesome.
Besides, with summer approaching us all. it could be useful to all of us
----
Buy a book. Read it.
Wally Plumley
928 Specialists
==========
At 04:49 PM 6/23/01, John Kunkel wrote:
>I've got an AC problem with my '87 S4. First drive of the day with the ambient temp in the nineties, I fire up the AC, temp control at minimum, fan at medium speed and the temp at the center outlet gradually drops to 35 deg F or less. After driving a while the outlet temp slowly starts to rise and eventually goes up into the high sixties. The heater hose between the two radiator hoses is hot, leading me to believe the valve is passing hot water to the core. I replaced the heater valve, same problem, so I'm thinking a malfunction in the controls might be sending vacuum to the valve allowing it to crack open a little. I'm going to deactivate the heater valve for the summer to see if this is the problem but I can't remember if vacuum opens or closes it. If I disconnect and plug the vacuum line will the valve fail open or closed? Any other ideas, comments?
> John
----
Vacuum closes the hot water valve. No vacuum, full heat.
A few things to check:
1) Is there a good strong vacuum to the valve? Check valve flow easily in
one direction, not at all in the other? Any vacuum leaks in the system?
2) Is the water valve installed correctly? If it is installed properly, the
water flow from the engine tends to push the valve disk onto its seat. if
it is installed backwards, the water flow tends to push the valve away from
its seat, and there will be significant flow.
3) Is the seal at the back of the hood there and in good condition? If the
seal is missing, hot air can flow from the engine compartment straight into
the HVAC inlet at the base of the windshield.
Wally Plumley
928 Specialists
=====================
could be the hot water valve but my guess may be the FREEZE SWITCH under the
rain shield.. under the hood...sits on the blower tunnel that leads to the
evaporator.. It shuts the AC of when the temp in the evaporator gets to
freezing.. something like that. My car had the switch bypassed when I
bought
it. I live in a VERY dry climate (Vegas) so moisture and freezing isn't
that
much of a problem.
Tony
======================
Dear John,
Assuming a good heater valve, as you state that you
recently replaced
it, I would think that you are not getting vacuum to the valve to close it.
The likely culprit is the solenoid inside the center console, or if you are
lucky, the rubber connector for the vacuum line either at the heater valve or
at the solenoid has disconnected. I will leave the repair sequence for
entering the center console and replacing the solenoid (one of five, see the
workshop manuals, page 87-104) to those with more experience. Both of these
scenarios have happened with me. Good Luck.
Jerry Magolan
=========
>
>BUT......
>
>In the afternoon with 100F, I get about 75F from the center vent, which is ok, it starts to fall, then after about 10 minutes, the compressor starts to cut in and out and no AC.... If I switch it off for a few minutes, it will start up again and fail after 5 or so minutes.
----
The compressor is controlled by:
The A/C controller. The little blue relay sometimes gives problems with
intermittent contact - but I doubt if it would be this consistently
temperature-related.
The antifreeze switch - but this is backwards to what I would expect if the
problem was low temps on the evaporator. That should be worse at lower
ambient temps.
Low pressure switch - also backwards.
High pressure switch - Bingo.
High pressure can be caused by:
Overcharge.
Low air flow over condenser.
Wally Plumley
928 Specialists
===
AC trouble
1) Crank the car, turn the temp control to full cold, fan on, etc.
2) Look at the A/C compressor pulley. Is the center of the pulley turning? If so, the compressor is engaged. If not, you may have an electrical problem, or the system may be empty.
3) If the pulley center (the clutch) is turning, feel the two lines from the condenser (the larger radiator-like heat exchanger in front of the radiator). One of the lines should be hot (125 to 180 deg F), and the other should be warm (100 to 125 deg F). If the lines are hot and warm, the compressor is working and there is freon in the system.
4) If the pulley center (clutch) is not turning, find the
receiver/dryer. This is the vertical can-shaped device in front of the
radiator on the right side. Kneel down and look thru the grille at the
receiver/dryer, and find the mushroom-shaped electrical switch. Pull the
two wires off of the switch, and bridge the wire connectors with the
engine running and the A/C on as in step 1. The A/C compressor should
start running as soon as the wires are bridged. If the compressor will
run with the wires bridged, but not with the wires plugged onto the
switch, the system is empty. Do NOT continue to run the compressor with
the wires bridged. If the compressor will not run with the wires
bridged, you have an electrical or control system problem.
If the system is empty, replace all of the o-rings at all of the system
joints before you have it refilled.
Wally Plumley
928 Specialists