Hi, I’m having issues with my AC;
The compressor, condenser and receiver dryer were recently replaced. system vacuumed and charged. blew cold air for a few minutes but it burns the #1 mini 10 Red Air conditioning clutch Fuse. I checked the lines and noticed that the high pressure line coming from the compressor that have the pressure sensor was hot to touch.
What could be causing this?

 

The "discharge hose" compressor to condenser will get hot when operating normally.
When working with any R 134 a/c system temperature can be converted to pressure.
If the system was not properly sanitized before installation of all the new parts it will be hard to determine what is going wrong. Normally a system will shut down if excessive head pressure is detected.. If the a/c clutch fuse is blowing you may have a problem with a wire shorting. You can check the coil with an ohm meter. If the resistance is between 3 and 5 ohms the coil is fine. Normally an open coil will blow fuses. if the coil checks out retrace the charging procedure. The system should have been put into a vacuum for at least 45 minutes to an hour before charging the system. This system only holds 28 oz of r 134. If overcharged or if there is any air in the system it will cause very high head pressure.

 

My opinion, offered for free and worth EVERY cent, is you have two separate issues at play. Actually, maybe just one, as the hot line is perfectly normal. I'm going with the assumption (I know, I know...) that the refrigerant servicing was done properly. Even if it wasn't, which would affect the cooling ability of the system, any improper servicing shouldn't have anything to do with the blown fuse.

Let's look at that #1 fuse. Does it blow repeatedly, or was it a one-time event? Does it blow right away or only after a few minutes?

The wiring diagram for an '01 V8 is here:

http://www.jagrepair.com/images/Auto...x2022001en.pdf


Scroll down to figure 01.3 to see the problem fuse. Note how it branches off to four separate circuits. Any one of them could be causing the fuse to blow, not just the circuit to the compressor clutch coil.

Fortunately, it's easy to isolate each circuit and see which one causes the fuse to blow, which in turn kicks off the compressor clutch. If you have an ammeter that reads 20A or so, remove the fuse and connect the meter in its place. I have one of these cheap ammeters for such occasions and it works great. It plugs right into the fuse socket and beats fumbling around with meter leads:

30 Amp Automotive Fuse Circuit Tester


Since your present concern is no AC, let's disable the other 3 circuits on that fuse and see if the compressor clutch will operate normally and not overload the fuse. From fig 01.3, we see the power from #1 fuse is distributed to blocks 67, 68, 69, and 70.

Follow block 67 to fig 03.2, and you can see how that power is controlled by relay #8 to engage the compressor clutch when commanded. Let's not disconnect anything there yet, as we want to see if the clutch will work with the other three circuits disconnected.

Block 68 and 69 both lead to fig 06.1 and control the auxiliary coolant pump via relay #5. If you unplug that relay, you have just eliminated the majority of circuits 68 and 69.

Block 70 also leads to fig 06.1 and is the power supply to the DCCV. Disconnect the plug at the valve.

By pulling one plug and one relay, you've eliminated nearly 75% of the potential problem areas. Pat yourself on the back for such great troubleshooting. If the AC now puts out cold air and the fuse doesn't blow, you know the source of the overcurrent was downstream of one of the disconnect points.

Try that and keep us posted.

 

In addition you could have a bad AC clutch on the compressor. Or did the new compressor come with a clutch too? Very common these days.

As was posted above see if unplugging some of the other items on that circuit can narrow the problem down some.

Have you hooked up gauges to check the AC pressures you now have?
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it was a use compressor; i unplug the pump relay and the compressor clutch fuse was still over heating.
i removed the fuse and used my volt meter to check voltage at the spot and when off i got 12.34 when the car was on i got 13.80.
i have the old compressor, i will try to remove the clutch and check it tomorrow.
as for the pressure; what should my gauges be at for this car?

 

Low fitting is right on compressor assembly. High fitting is right on accumulator. Pressures are temperature ambient. General rule of thumb. Low side 25 - 40 and high side 150-200.

Now, to my disclaimer: no offense, but...)

Please do not attempt reading pressures unless your familiar with AC diagnosis, testing and proper filling procedures as you can damage your AC system and yourself...

 

Did you also try unplugging the connector on the DCCV? That was the other potential source of the short that keeps blowing the fuse. However, if the fuse wasn't blowing before you changed the compressor, then the replacement is your most likely culprit. Sorry I didn't think of that yesterday before posting my treatise on troubleshooting. But I just had another thought: Could the fuse have been bad before you changed the compressor? Might be something to consider.

Before going to the trouble of swapping the compressor clutches, try setting the old compressor on the ground near the installed one. Disconnect the plug from the installed compressor and use a pair of jumper wires to connect power and ground from the old compressor to the vehicle wiring. Turn on the ignition and AC to see if the old compressor clutch clamps down and the fuse stays intact. I'm not sure if the engine must be running for the clutch to engage, or if turning on the ignition is enough. If you have to run the engine, make sure everything is clear of any moving parts.

As far as the gauge readings, I personally wouldn't worry about that right now. Take care of the blown fuses knocking out the compressor clutch. Once you get that fixed, run the AC system and see if you get cold air. If so, you're good.

Although you didn't specifically ask, please be aware gauge readings can NOT tell you if the proper amount of refrigerant is in the system. The gauge readings can help determine compressor performance and other factors, but not the quantity of refrigerant.

 

Another point to consider. Some clutch coils have a diode in them. If wires were crossed it would blow the diode and can cause fuses to blow. If that's the case the clutch hub is trash and will need to be replaced. The simple ohm check I suggested before can tell the tale. between the pins on the clutch connector a reading outside of 3 to 5 ohms is a bad coil or blown diode.

 

Now since you installed a used compressor we have a whole new ball game!!

I would NEVER put a used compressor in. And you are finding out why. AC Compressor's, water pumps, brakes, belts, hoses are are all wear parts. They need to be replaced with new or rebuilt parts.

Please tell me you at least put a new dryer in with this used part? It is mandatory! That is another big strike if you did not. Again if you don't know or understand the AC system you are screwing it up big time!

The compressors for our Jags are pretty cheap and all over EBay. I hope that used part did not contaminate the rest of your system. AC systems must be 100% clean. You have not put any stop leak or other crap in the system have you? Only R143a.

Too late now but follow the 2 suggestions above.
1. Check ohms on AC clutch
2. Unhook DCCV to see if the that is what's blowing the fuse.

Then report back.
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new dryer was installed during the condenser change (old condenser was leaking). reason for the used compressor was because i had 2 new alternators and both didn't work properly. a friend told me unless it is an original alternator i will always have the battery light on the dash and some functions wont work properly; so he recommended that i get a used oem one.
I'm working through a few things. i bought the car needing an engine replacement which i did; new fuel pump, alternator and now i'm working on the AC. so its a project for me. i have worked on all my previous vehicles but none as sensitive as this car.
learning as i go along.

 

I forgot to mention you can do this by unplugging relay #8 and measuring from the socket. It's a lot easier than crawling under the car.

While you have that relay out, you can also confirm if the compressor clutch was the cause of the fuse blowing. If the fuse only blows when you reinstall the relay and turn on the AC, you've narrowed down the culprit. There's a slim chance the wire could be rubbing against a ground, so next unplug the compressor clutch to be sure.

 

was the condenser New or used? If it is a used part.You will need to start over with new parts. A re-manufactured compressor should be ok if the rebuild was done by a company that does that as a business. I am in the a/c parts business and never suggest a re built pump unless new is not available or there is a $200 cost difference. Good luck. Be patient do all the voltage checks and ohm checks. There is always a solution to a problem

 

Sorry if I got off track but a used alternator is fine. Yes we have seen numerous aftermarket alternators cause red battery lights. The best suggestion is to rebuild your original. Usually cheaper too.

So just to make sure I understand? It was a used alternator AND a used AC compressor?
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yes after having issues with the aftermarket alternator i get a use one. i havent replaced the aftermarket alternator as yet. i'm waiting on my new AC compressor so i can do both swap the same time.

this car has been a project for me; the AC and speedometer is the last 2 on my list.
i have not had the chance to look at the wheel hub assembly as yet as i believe that is the issue.

I've replaced;

engine
radiator
water pump
ac condenser
fuel pump
alternator
ignition coils
center console (arm rest)

by the end of the month i will have the new ac and alternator installed and provide an update this!

it's not my main vehicle so one step at a time.

thanks a lot everyone!!!

 

Use this link and go to page 117. Not sure what you have going but a bouncing high side pressure would be an indication of a blockage or a bad expansion valve. If you are going to replace the compressor with new you need to flush the system anything less is a mistake take it from one that knows.

Link http://jagrepair.com/images/Training...des/703_SG.pdf

 

update
dennysjag was right!

An open coil was the cause of the blow fuses.

changed the AC compressor, vacuum and recharged the system now it's all good! thanks a lot guys!