Ptipon
(Ptipon, Sonora, CA, USA, 1990 XJS, Conv.)
1
I came back with another can of freon to top off the system and guess what.
I let the car cool down for half an hour, hooked everything up to insert freon and the pressure gauge reads in the 'Red, ,
'. I then started the engine and turned the air on ‘full tilt’. The compressor is not running as the clutch does not
seem to be engaged and the pressure still reads in the ‘Red’. And basically no more cooling.
Now what ? I disconnected everything and I’m going to let it sit for a while to see if anything changes.–
Ptipon
Modesto/CA, 90 XJS-V12 conv, United States
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In reply to a message from Ptipon sent Tue 11 Jun 2013:
I’m assuming you mean that the gauge on the can of
refrigerant reads in the red.
I’m afraid it’s going to be difficult to diagnose for you.
The manual I have only tells you ranges based off the high
pressure side of the charged system. Your reading comes
from the low side. What’s worse is that ‘‘red’’ area could
be absolutely fine for some cars and not so good for
others.
You’re going to have to get a manifold (which some parts
stores rent out for free) to have any chance at diagnosing
your problem.
As far as I can tell, the only way to know of your system
has the proper charge is to evacuate it and recharge it
with 32oz ± 1.5 oz… And I think that is only for the
95-96 MY.
The manual does say that the low side gauge should read
15-30psi. I do have a chart that correlates the low side
with evaporator temperature…if you can get to that!
Lastly, and I know you know this, topping off is not a
good idea. You really should invest some money to fix the
problem. It cost me $95 to have my shop find a leaky
condenser. I replaced it myself, and you can too!
The high side readings are dependent upon the ambient
temperature.–
1996 XJS 2+2 Convertible with 4.0L AJ16
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In reply to a message from Ptipon sent Tue 11 Jun 2013:
The readings are not terribly meaningful until you get the
compressor turning. There is a fuse and a couple switches
that can prevent the clutch from engaging. I’d start at
one end of the circuit and follow the power with a volt
meter till you find what has it stopped.–
John. '95 XJS 6.0L convertible. Southlake, TX
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In reply to a message from Ptipon sent Tue 11 Jun 2013:
Scratch that.
I can confirm that those numbers are for R12 only.
There is no chart that I am aware of for r134a. It’s
seems to be as simple as evacuate and fill with 32oz of
refrigerant.–
1996 XJS 2+2 Convertible with 4.0L AJ16
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I let the car cool down for half an hour, hooked everything
up to insert freon and the pressure gauge reads in the 'Red,
If your car has sat for a short time the AC pressure will stabilize. This means the low side will increase and the high side will decrease. The average pressure will be over the fill can spec and gauge reading will be in the red. This red zone warning is to let you know you are not filling the system and may be filling the can in your hand. The burst pressure on a can is lower than the system can make on the high side.
Normally the system is filled on the low side at about max pressure of 30 psi with the operating low side system near 10 to 15 psi as the system switches the compressor on. Again this will rise to the average pressure when the compressor is off for a while.
R 134 systems are filled by weight. However you need to monitor the high and low side pressure and outlet temp to find the sweet spot. When the high pressure stops rising and the temp stops lowering that’s it. Near the suggested fill weight.
Ptipon
(Ptipon, Sonora, CA, USA, 1990 XJS, Conv.)
7
Thanks Geoff,
This is going to sound quite stupid but after checking all of the
electrical on the compressor clutch, I realized that I didn’t have
the air on. Self elected humility is good for one’s soul every once
in a while especially with the gut chuckle that follows.
So now I have put in 2 full cans of 134R but still have more than
half of the green area to go.
How many cans does the system take ?
Ptipon
Modesto/CA, 90 XJS-V12 conv, United StatesOn Jun 11, 2013, at 8:29 PM, Geoffrey Green wrote:
I let the car cool down for half an hour, hooked everything
up to insert freon and the pressure gauge reads in the 'Red,
If your car has sat for a short time the AC pressure will
stabilize. This means the low side will increase and the high side
will decrease. The average pressure will be over the fill can spec
and gauge reading will be in the red. This red zone warning is to
let you know you are not filling the system and may be filling the
can in your hand. The burst pressure on a can is lower than the
system can make on the high side.
Normally the system is filled on the low side at about max pressure
of 30 psi with the operating low side system near 10 to 15 psi as
the system switches the compressor on. Again this will rise to the
average pressure when the compressor is off for a while.
R 134 systems are filled by weight. However you need to monitor the
high and low side pressure and outlet temp to find the sweet spot.
When the high pressure stops rising and the temp stops lowering
that’s it. Near the suggested fill weight.
So now I have put in 2 full cans of 134R but still have more
than half of the green area to go.
How many cans does the system take ?
Paul,
The green area means you are in a safe fill zone. Has nothing to do with getting the correct amount in. You have to go by weight. If it takes 2.5 pounds then you have to put in 40 oz. If the cans are 14 oz then you need about 2 and 2/3 cans.
I do not know what a 90 V12 XJS takes in weight. Probably close to other XJSs including those with the I6. If someone knows the weight needed please post and we can have an aproximate amount, Another way to go is to put a temp guage in the outlet, ac on high max cool and fill it until the temp stops dropping. You need to fill slowly towards the end to allow the system to adjust and register the change on the thermometer.
The green zone on the dial means the can will not burst in your hand.
Ptipon
(Ptipon, Sonora, CA, USA, 1990 XJS, Conv.)
9
Thanks again Geoff,
Very cool this thread is now complete as to how to top off the AC
correctly when the weight amount gets posted. When it comes up I
will jot in down in my shop manual. I will also see if that weight
is posted there. I have a complete set of dealer shop binder manuals.
Ptipon
Modesto/CA, 90 XJS-V12 conv, United StatesOn Jun 14, 2013, at 8:00 PM, Geoffrey Green wrote:
So now I have put in 2 full cans of 134R but still have more
than half of the green area to go.
How many cans does the system take ?
Paul,
The green area means you are in a safe fill zone. Has nothing to
do with getting the correct amount in. You have to go by weight. If
it takes 2.5 pounds then you have to put in 40 oz. If the cans are
14 oz then you need about 2 and 2/3 cans.
I do not know what a 90 V12 XJS takes in weight. Probably close to
other XJSs including those with the I6. If someone knows the weight
needed please post and we can have an aproximate amount, Another
way to go is to put a temp guage in the outlet, ac on high max cool
and fill it until the temp stops dropping. You need to fill slowly
towards the end to allow the system to adjust and register the
change on the thermometer.
The green zone on the dial means the can will not burst in your hand.