Air conditioner pressure question

ford
zx2
airconditioning

#1

I have a 98 Ford Escort ZX2 and the the ac is not working. I was going to recharge the system but when I checked the pressure I got a really high reading on the low side and a low reading on the high side. Does this mean my compressor is faulty?


#2

I conclude you used a dedicated set of gagues 9not the charge bottle version) and the car was running.


#3

Give us the numbers. With the compressor off, static pressure should be less than 90psi and equal on both sides. Running pressure should drop quickly to near 30psi on the low side and over 150psi on the high side. Beyond that, there is a great deal of system and condition specific parameters to deal with. It’s really better to become familiar with how the system works before attempting to do any work on it.


#4

Ok - first, A/C systems are really not good DIY items. Unlike many other things on the car they really do require training and the right specialized equipment.

With that disclaimer noted - you have to figure out whether or not the compressor is running at all. If the system is very low, the compressor will not run. In that case the pressure will actually be high, but the refrigerant level is actually low. Sometimes refrigerant has to be added to get to a level where the compressor will run. With the compressor running the low side pressure will drop - b/c the compressor is, well, compressing.

But this is where things get tricky for the DIY’er. It may be that the compressor is not running for some other reason and the system doesn’t need to be charged. Overcharging the system is very bad.

The directions that come with those recharge kits probably tell you that if the compressor doesn’t run to add a can to see what happens. If you add a can and the compressor doesn’t run it should say to stop and see a specialist in AC systems.

If I were you, I’d bite the bullet and take it to someone who knows AC systems.


#5

I purchased a set of gauges from my local parts house and checked it with the car running.


#6

I noticed that the clutch on the compressor is not spinning when the ac is on. I’m just going to spend the money to get it looked at. Thanks for the help.


#7

A pressure switch prevents the compressor from engaging when the freon pressure is too low…You could re-charge it, but it would just leak out again…


#8

So I talked to a tech at Ford and they said a common problem with the Escort is the Constant Control Relay Module which controls the compressor clutch(among other things) will go bad and they replace them all the time. A new one from a parts store will cost around $180 so I’ll be at the junkyard looking for one.


#9

Are you saying that you have a diagnosis of a bad CCM? B/c replacing it just on the basis of “they often go bad” is a really bad idea - especially with one from the junkyard.

How about some actual diagnosis?


#10

You went and spent money on gagues but you resort to somebody’s statement about “these always go bad”? You probably should have just saved the money on the gagues if you repair based upon a “this is always the problem” basis.


#11

How often is the best advice TAKE IT TO A SHOP OR LEAVE IT ALONE. I don’t open most threads here, maybe not 1/4 of them. But of those, I often suggest getting help or later wish that I had.

And, BTW, is Fast Jeff, Slanter, Impala, Mrs AOD, or any of the posters from the old Rant and Rave dropping by here on occasion?


#12

I just can’t see buying gagues and then repairing on a “known failure” basis. The last set I bought cost over $100.00 but Harbor Freight probably has a 39.00 set.