My girlfriend has a 1992 Toyota Tercel. Of course on the hottest day so far this summer the air conditioning stops working. The problem is when you hit the button to turn it on nothing happens. Blower works fine and all the vents are working fine. The compressor doesn’t even attempt to enguage. Also the light on the switch does not come on. This makes me think it’s something electrical. I looked in the fuse box under the hood and found the AC fuses. However they are more like “modules” than fuses. I thought perhaps there is a relay in them that may have gone bad and caused everything to stop working. Anyone know anything about whether or not these modules can go bad before she spends $60 on a computer diagnostic?
How about the switch itself? It’s a moving part & may have worn out. If the indicator light (I’m assuming the switch has one built in) isn’t coming on then there ain’t no juice going THROUGH that part of the system. That would be because a) the switch is busted or b) the problem is upstream of the switch.
Remove the switch, grab a little christmas light, a flashlight battery and some wire. Make a little circuit & see if the switch can turn the light on & off.
Do this IN FRONT of your GF. If this truly IS the problem then, well, the switch really DOES work but just not like the manufacturer intended.
I’m sure that what you’re calling modules can go bad. So can quite a few other parts of the A/C system. The significant question is arethey bad. Your choice is diagnosis by testing or diagnosis by parts replacement.
If you guess wrong about what parts are needed, diagnosis by parts replacement can get pretty darned expensive.
If I’m not mistaken, on that system even a loss of refrigerant (“freon”) can cause the symptom described–there may not be any electrical fault.
The electric clutch on the compressor is another wearing part that can go with some regularity. Usually not cheap either. I’d recomend you/she spend the small bit of dough to get it diagnosed by a professional as opposed to what GaryT mentioned, diagnosis by replacement if your not darned sure.
Good luck!
Some cars have a fuse located in the AC duct-work, usually in the engine compartment.
Another possibility is, if you are low on refrigerant the clutch will not engage.
Another vote for “loss of refrigerant.” My aging car (also a 1992, by chance) was displaying exactly the same symptoms described in the OP - no sudden load on the engine, no reassuring little blue light. To me, that said “electrical problem.” But a visit to my local friendly mechanic confirmed that the refrigerant was gone, and a refill cured the problem, with no other work being necessary.
Like my car, however, the OP’s GF’s car can’t just be refilled with refrigerant, since it’s from the Freon era. The car’s A/C system will need to be converted to the new refrigerant (R-134?), which will set you back at least $350, assuming nothing else needs to be done.
Wal-Mart has a kit for about $40-50, that includes the tools and fittings to convert from freon to 134. I’ve done three vehicles so far and they work fine. (not quite as cold) but for $4 a can NO PERMIT REQUIRED it takes less than ab hour and anyone with minimal mechanical ability can/should be able to do it.
First thing I’d do if I was worried about a leak. If I couldn’t locate it w/ soap&water, would be to inject a can of dye into the system. I suppose checking to see if there is ANY freon in it at all would be good to know. Just quickly press the needle valve on the coolant line while the car is off. You’ll know immediately if there’s freon in the system.
It’d be nice if you had a gauge to check the pressure. $10 - 15 at autozone. Check the specs. in your owners manual for #pressure.
If there is NO freon in the system you definitely have a leak, at the very least. If there is no freon in the system you can pull the compressor and have it checked at a parts house. Replace if needed. Last one I bought was $100 last year.
Go ahead and buy new filter and condenser etc. another $20-30.
Put the parts back on the system and fill w/ dye. (NO FREON 134 YET) Hopefully it’ll kick in. (if not you’re still not out anything you didn’t already need)
This means it’s electrical. We’ll get to that later.
If it does kick in, the dye will leak and reveal the problem. Usually leak are found at coupling where O-rings have deteriorated. Get a set (very inexpensive) and replace all the ones you can find.
Try it again, odds are that’ll take care of your leak. Unless its a split line. Those can be removed and replaced as well.
Get a 134R kit and follow the instructions…
I gotta go, but if you want more just let me know…bye
BTW you might try bi-passing the switch and run a jumper wire to the compressor to see if it even works before doing anything.
AND the “fuse box” does have relays which control the AC.
(specs should tell you which)
That’s not true. It is possible and legal to service it with R-12. The stuff is expensive, but recharging the system will cost less than doing a complete and proper conversion to R-134a. Some shops have chosen not to deal with R-12, and only offer R-34a service. But R-12 is still available, and there are still shops that service it.
I know you’re trying to help, and I’m glad you’re happy with what you’ve done, but there’s a lot of key info wrong or missing there.
First thing I’d do if I was worried about a leak. If I couldn’t locate it w/ soap&water, would be to inject a can of dye into the system.
Soap & water is not a reliable leak detection method on automotive A/C. Only large leaks in convenient places could be found. The standard methods are an using an electronic leak detector, and dye insertion if there’s suspicion of a small leak that won’t register on the detector. If the evaporator is leaking, which is fairly common, only a leak detector will find it.
I suppose checking to see if there is ANY freon in it at all would be good to know. Just quickly press the needle valve on the coolant line while the car is off. You’ll know immediately if there’s freon in the system.
It’s a refrigerant line. Coolant is in the car’s cooling system–radiator, engine block, etc. If there is anything in the system, it will need to be removed before adding a different type of refrigerant. The legal and environmentally responsible way to do that is with a reclaiming machine. But knowing there’s some refrigerant in the system is different from knowing there’s enough in the system, which is critical.
If there is NO freon in the system you definitely have a leak, at the very least. If there is no freon in the system you can pull the compressor and have it checked at a parts house. Replace if needed. Last one I bought was $100 last year.
Pull the compressor? Why? It’s no more likely to be leaking than the hoses, connections, evaporator, or condenser. And I’d sure like to know how a parts store can test one–for either leakage or performance. I’ve never heard of such a thing.
- Go ahead and buy new filter and condenser etc. another $20-30.*
You might be able to get a receiver-drier or accumulator (what I assume you mean by filter) in that price range, for some cars. Figure ten times that for a condenser–and condensers aren’t replaced unless they’re leaking or restricted. Unless you have an extra 200 or so that you don’t need.
Put the parts back on the system and fill w/ dye. (NO FREON 134 YET) Hopefully it’ll kick in. (if not you’re still not out anything you didn’t already need)
This shows no grasp of what’s going on. The system will not kick in unless it has some refrigerant in it (needs to have 40+ psi of rest pressure). And you shouldn’t put anything in it until it has been evacuated–otherwise, there will be a significant amount of air and moisture in the system. Air will noticeably hamper its performance. Moisture will form acids which erode the components from within, and sometimes freeze up in the pipes and prevent cooling.
If it does kick in, the dye will leak and reveal the problem.
It often takes days or weeks for dye to show up externally at the leak(s).
Then there’s the matter of following EPA regulations about changing the service fittings to the R-134a type. And applying a label stating what type of refrigerant is in the system. And making sure it has a high-pressure cut-out switch, installing one if it doesn’t. Etc.
What you’ve described is not a conversion to R-134a, it’s just adding R-134a to the system. Big difference.
This will give an idea of what’s involved in doing a conversion/retrofit the right way: http://www.dmcnews.com/Techsection/r134.html
Correct, but around here, there just aren’t any mechanics who are willing to deal with it. They’ve simply abandoned R-12 entirely, so if you have a problem with your R-12 system, you don’t have much choice other than to get it converted (I believe you have to be licensed to work on an R-12 system, so DIY isn’t a realistic option, either).
Sorry guys I was at work all day. Thanks for all the suggestions. It looks like most of you think that the system is out of freon and causing the compressor not to kick on. I’ll go ahead and get a guage and check the pressure and see if there are leaks. If it is low on freon I have an EPA permit that allows me to purchase it I believe.
Sorry to hear you don’t have that option in your area.
You do need a license to buy R-12. I’m not aware of any licensing needed to actually work on it. Professional repair shops are subject to EPA regulations, particularly as far as reclaiming refrigerants rather than releasing them into the atmosphere. My understanding is that the regulations don’t apply to individuals working on their own cars. The big obstacle would be obtaining the R-12.
In all this talk about refrigerants, I think the likely root cause is being left out.
The OP said:
I think Matchka’s first response was the most on target. I have no idea whatsoever what Matchka’s second response means, so lets just leave that out of it! 
If the light on the switch doesn’t work, and you already checked the fuses, it is most likely the switch itself.
It certainly could be the switch. However, the symptom doesn’t preclude other possibilities. Japanese cars tend to have clever, and sometimes intricate, electrical circuit designs. I’m pretty sure the system is designed such that power is not sent to the on/off switch if the low pressure switch doesn’t register adequate refrigerant rest pressure. Refrigerant loss is much more common than switch failure, and could give the very same symptom.
While I don’t doubt what you say, the switch would be the logical first step and also the easiest thing to check for someone like brainchild876 with no special tools or professional knowledge. If it turns out that the switch is fine, I probably wouldn’t recommend that brainchild876 delve into the problem much further without the expertise and resources of a certified professional.
When it comes to my own DIY’ing, I know my own limitations and when something is over my head I don’t attempt it. (Not to mention that my condo association doesn’t take kindly to anything more than the most basic auto repairs. No oil changes, no cars up on jacks unless it’s just a quick wheel change, not even car washes for that matter…)
Besides, working without the proper tools and knowledge will usually end up costing more in replacing parts unnecessarily and could cause further damage. This could result in danger to the safety of your car, yourself, and the environment. Not to mention that it will make the professional’s job of diagnosing and fixing the problem much more difficult when you give up and bring it to them after futzing it all up.
Oh yeah, I knew I had more in mind that I forgot to say before clicking submit…
Based on the limited details of the OP, it sounds to me that the problems started all of a sudden. I own two Japanese cars, a Honda and a Mazda. I have experienced problems with lack of refrigerant pressure in both. In fact, the Mazda is currently experiencing the problem and the Honda has in the past. In both instances, the problems manifested themselves slowly with a gradual loss of cooling. In both instances, the switch continued to light up and work like normal and there was a very noticeable “clicking” noise coming from the compressor whenever the A/C was turned on, particularly at idle. I believe that this is a common symptom of the lack of sufficient refrigerant pressure in the system.
I know that my anecdotal experience with two totally different cars might not apply to the OP’s car, but I hope that they might help the diagnosis in some way if any of the symptoms or observations are similar.