I dare you to look at my AC question

I am having a problem with AC not kicking in. I don't think that the refrigerant level is low because it worked fine just a couple days ago. But I did notice some peculiar behavior leading up to this issue.

Based on some observation; when my AC has been prissy and not kicking in the past (has happened about two other times), it seemed to start acting up after having run the AC for a short time, i.e. drove a short distance like from one house to another in the same neighborhood or driving from one store to another in the same shopping area. When starting the AC after that, it seems to just not want to kick in. This is of course not universally the case and I have driven very few short distances without problems, but I mostly drive long distance, so the relationship has been noticeable.

Last times this happened, a night?s rest resolved the issue, but it has been two days now! To clarify, then I mention that the AC does not kick in, I mean nothing happens! No cycling, no sound, no taxing the engine? nothing. There is no slightly cold air and there is no sign of life - that is noticeable for me -from the AC system.

I am sure someone will suggest having it ?diagnosed? (read: paying less qualified people more money to have a machine tell them to tell me that there is nothing wrong with the AC system), but is there something I can do to check some electrical things like whether the compressor is getting juice or if the temperature sensor is working properly?

I would greatly appreciate if you have any other suggestions for tests or diagnosis I can do to get an idea of what is going on. I would greatly prefer to not drop a bunch of money at a dealership or mechanic (not a lot of reputable mechanics where I live?. Merchant?s is definitely not ethical or reputable) for some AC work that will simply patch the problem because they can?t find a problem. If I sound cynical; it?s because I am and have left good money at repair shops that got nothing done.

Check and see if the A/C has a relay in the circuit and replace that. That is about all I can suggest at this time.

No one is going to be able to tell you anything without knowing what the high and low pressures are for starters.
You “don’t think” the refrigerant level is low? That’s about as non-scientific as it gets.

You do not want to spend any money on an A/C system on a 10 year old car with 165k miles so your options are pretty limited. Odds are there is a leak)s) in the system and the refrigernat level is low which in turn may cause a pressure switch to not function properly.

I seriously doubt your area is plagued with a lack of reputable mechanics. However, you will very likely run across a number of mechanics who will refuse to fix your car on the dirt cheap or for nothing.

Sometimes finding a real Auto AC specialist is the key. Their experience level far exceeds most general mechanics, because they work or install these systems daily. Have you checked cartalk.com’s mechanics files for some recommendations? Merchants is just one of many chains that may or may not pay to have good quality mechanics on board, and their inability to hire good quality folks impacts the diagnosis quite a bit (guessing and parts replacement vs true diagnosis). That is why many of us recommend finding a good independent mechanic based on mechanics files or word of mouth.

You can check the fuses under the dash and hood. You could also see if voltage is getting to the clutch of the compressor. If not then you may want to check the relay and see if that is ok. If you want to check things further I suggest you purchase a service manual for the vehicle. It is one of the best investments you can make in your car if you like to work on problems like this yourself. It will save you time and money.

I agree that “don’t think the refrigerant level is low”, is not very scientific; but I don’t have a way to read the high side. I have a gauge to read the low side, but since the compressor does not kick in, the levels are extremely high. But I can’t tell you what they are off the top of my head; 140 PSI maybe. I will check if that will help considering that, I assume, if the compressor is not kicking in, the levels should be equal on the high and the low, right?

I want to spend money on the AC system, but so far, the hundreds of dollars I have blown on diagnostics, inspections, recharges, etc. have gotten me nowhere. I am tired of blowing around $120 every time I want to have someone resolve the problem, just to be told that “we couldn’t find a leak, but we recharged the system”. I have heard that about five times now.

The problem with mechanics is twofold where I live. One, affluent people and tourists do not like mechanics shops, hence very few shop options around. Two, I don’t have enough experience with the mechanics where I currently live to make an informed judgment as to which is not going to rip me. I would like to get it fixed and I don’t mind paying for it (don’t judge me based on the car, it is a matter of being environmentally responsible for me), I just get friggin’ ticked off when I throw good money after bad without any results. I would have even loved to just hear what it would cost or what the problem is.

Thank you for your response though, even if it had a bit of a prejudice tone.

Thanks for the info!

Do you have any idea in what general vicinity the relay may be located?

Everything on a car/truck works right up until the time it stops or breaks. So saying it’s not a freon issue makes no sense. Withoput knowing the high and low side pressures no one can help you. The vehicle has pressures switches to stop the compressor from turning on when freon level is low.

Sorry but if you want A/C you’ll have to break down and spend some money…I DARE YOU SPEND A FEW BUCKS

Yes, check the voltage at the compressor clutch,low voltage could be your concern

Buy a simple circuit tester, the kind that looks like an ice-pick with a wire attached and start looking for power. At the compressor hub, you will find a 2-wire connector. One is ground and one should be “hot” when the engine is running and the A/C is turned on. On many FWD cars, just accessing the A/C compressor is a half-day job. Your 140psi sounds like enough to allow the compressor to kick in…You can temporarily “hot wire” the compressor and see if it kicks in…This can be done with the engine off…On the low-side return line, somewhere near the fill port you have already found, is the low pressure cut-out switch. It usually has one wire in and one out to the compressor or relay. With the engine running and A/C switched on, both sides of that switch should be hot…Good Luck…

You’re correct that both the high and low side pressure will be even when the system is turned off. (This is after it settles down a bit).

The pressures will vary because there are so many factors (humidity, ambient air temp, state of charge, whether the vehicle is facing the sunlight, how bug clogged the condenser is, etc., etc. so about I can offer is a general rule of thumb.

Normally, the at-rest pressure (static pressure) of the system when it is not operating will normally fall around 120-125 PSI or so. A 140 might be a bit high.
If the 140 PSI is the high side pressure when the compressor is engaged then that is way too low and you’re either suffering from a refrigerant undercharge or a compressor valve problem.

As I said, the pressures will vary but one should generally look for about 35 PSI on the low side and about 250 or so on the high side. (With a proper charge and about 1500 RPMS on the tach.)

About all I can suggest is have someone check the pressures at elevated RPMs or purchase a set of inexpensive gauges. I’m always a bit hesitant about advising someone on A/C service because it can be a bit dangerous.
However, if you choose to buy a set of gauges the R134 systems are designed so that the high and low side gauge fittings will only connect to their respective service valves. They’re different sizes and it’s impossible to cross them up.

If you decide to go the DIY route post back and at least receive a few pointers before wading into this. Refrigerant being vented instantly into the atmosphere can cause frostbite in seconds and blindness instantly if refrig. hits the eyeballs.

If I had to make a wild guess here, I’d say that you probably have a compressor shaft seal leak and the refrig. level is low. The shaft seals are the No. 1 source of most leaks IMHO and considering the age/mileage it’s perfectly normal for a leak to occur there.
Hope that helps.

I am having the exact same problem with my '98 ZX2 right now (160,000 miles). I haven’t bothered to diagnose it yet because it always comes on again eventually so far. I’d like to wait until it quits altogether because it will be a heck of a lot easier to find. I suspect the AC relay which on this car is included in the so-called CCRM (Ford’s “constant control relay module”). This sealed black box has some other relays in it too. I noticed another post on this board where someone was able to open this module by drilling the rivets and replace a single relay for cheap. The whole unit might run $200 or so. I believe that on my car there is no low pressure or any other problem with the system. It’s got to be a simple electrical issue.

per AllData, the relay is included in the CCRM module. I think it’s located under the intake air tube. It has a big multi pin connector going into a little metal box.

If you had read my response, you would have seen that I have spent several hundreds of dollars trying to find the solution to the AC acting up over the years. I just want to do some of my own investigation, because as I have found in other instances, when I do my own investigation, I can point the mechanics on the right path. Until I find a good mechanic, I will have to continue doing this.

I am simply looking for pointers, that’s it.

I would have to agree in thinking it is electrical related. Although I have not been able to get intimate with the compressor electrical as suggested due to it being hidden away behind splash guard and only accessible from under the car, but the refrigerant does not seem to be low and I can’t get the system to do anything. I don’t really have any time to get dirty, so I am hoping it will stay dead until I can get it to a shop some time this week. It looks like I found an old school shop that might offer some experience that can locate the problem.

I will try to post the results, if I get any.

The problem I have been having seems to be resolved. Following a good ol’ fashion diagnostic it was determined that the switch that engages the clutch was bad. So, after swapping out the whole compressor and clutch because there was apparently no good way to tell if the compressor was also bad, and most of the cost was labor, it made some sense as an insurance.

The system has been running fine now without a single problem.

You could have applied voltage direct to the clutch to get the compressor to run.You feel OK replacing a compressor when the problem was just a switch.Best laugh today.

Sounds like a lot of time consuming and expensive guessing when the problem may have been nothing more than a slight loss of refrigerant charge which would cause the low pressure switch to remain open - and no power to the compressor.

Also, diagnosing a compressor is not guesswork; it’s either noisy or there is a problem with the high/low side pressures.