About $30, according to my prelimanary googling. Although I guess I never googled Michigan specifically…crap, back to Dr Google I go.
Can a good auto repair shop tell me whether my AC needs charging or whether I need a new compressor?
The trouble is that even with the DIY kits that have a (single) gauge, there’s still a chance of damaging the system, especially if (like mentioned earlier) the system might have zero pressure. So in trying to save $40-50 you could turn an $80 problem into an $800 one.
If I were you, I’d try calling around and presenting this dilemma to different shops and seeing what they quote you to diagnose it. Ideally I’d say take it to an AC-specific shop, but I’ll bet you don’t have those there. But still there’s shops that have the AC machine and know how to read the manual and there are those that genuinely specialize in AC. I personally think keeping the AC working is worth at least $80.
Agh.
OK…well I will ask around IRL first, but the van is going in for a tune-up and various fluid changes later this week at the shop I trust most. I will ask them about this.
Dr Google keeps revealing anecdotes about horrible things that can happen with DIY AC kits. I suspect I’ll probably do my part in stimulating local economy and have the shop look at it and do their thing. I didn’t really want to be a cheap bitch about this. Just didn’t want to spend unecessary money.
The DIY kits generally work just fine for simply topping off the refrigerant, but for a completely non-functional system it’d be a bit of a gamble.
Keep in mind that google is a self-selecting system, the folks with problems are the ones posting. Here’s a positive anecdote:
My Subaru’s A/C stopped running. The first thing a shade-tree mechanic will do is attempt to find the source of the leak. Right next to the r-134a cans with dye (for troubleshooting with a black-light) is a can that has r-134a, the dye, and a stop-leak additive.
Well if I had to refill it anyway to test, I might as well throw the stop leak in there.
That was two years ago and the system is still running great.
Obviously, if you have an r-12 system, that won’t work for you, but a can was, like, $12.
I had a second vehicle that would only engage the compressor if the engine was off-idle. That’s either a low-pressure safety-switch gone bad, or low refrigerant. Swapped both for $30, and THAT car is still running happily.
Had another car that just needed to have a low pressure switch replaced (careful shorting of that circuit had the system blowing plenty of cold air).
Part of the cost in having someone replace the compressor is that they also replace the accumulator, as that’s where all the shavings go when the compressor fails…they also blow out all the lines to clean out the crud. There’s really no ADDITIONAL damage you’re gonna cause if the parts are shot already.
The problem with DIY kits is you have no clue as to what is in the system to start with, and what you are doing to it by adding an arbitrary amount of gas. I highly doubt there is one DIYer in a 1,000 that knows how to interpret various gauge readings correctly.
Pop quiz:
Example 4 cars 2 have problems, 2 don’t what is up with these readings? Add 1 can of R-134 to each.
Car #1 gauge reads 30PSI, added 1 can and cooling still sucks
Car #2 gauge reads 40 PSI added 1 can and cooling sucks
Car #3 gauge reads 25 PSI and cools great
Car #4 gauge reads 40 PSI and cools great (see end of post for answers)
[/nitpick]Well maybe. [/nitpick]
- Not all cars are set up to do this
- If the temp of the gas in the system is below about 45F, compressor will not engage due to not enough gas pressure in the system to trip the low pressure cut out switch. Until the pressure in the system will come up high enough, the low pressure switch will interrupt current to the AC clutch.
Once the pressure does come up (the heater and the engine will both bring the temp and pressure in the AC system fairly quickly) the AC system will cycle on and work it’s magic.
Some slight advantage? Never played with an integrated climate system I see. That is unless you call an order of magnitude a slight advantage.
Without AC as you drive in the winter water vapor (from your breath, your sweat, the snow on your boots, the rain that soaked into your jacket, and moisture in the outside air) is warmed by the warm air in the cabin. The glass is cold. If the glass is below the dew point, the water will condense on the cold glass. First the side windows, then the back window, and finally the edges of the windshield. Turn on the AC and within seconds the windows are clear.
If the glass is cold enough water will condense. I was in NY once in the summer 97F and humid as hell. Finished work and headed for the hotel and a cold beer. About half way to the hotel, I look in the rear view mirror and find my rear window is fogged up. So I go to look at my left door mirror, the left window is fogged up. WTF?
I know that the air inside is dry, but I reach over and rub the fogged up part. The glass is dry. :eek: On my side.
the AC had cooled the windows to the point that water was condensing on the outside despite it being hotter than hell out there. I had to turn on the Rear window defroster to see behind me. The point is no matter what the temp on one side of the glass, if the temp on the other side brings the glass down to below the dew point, the glass will fog.
*Answer to pop quiz:
Car #2 Is from the 80’s and has been converted to R-134 takes 3.5 lbs of R-134. System was almost empty, 1 can brought it up to about 50% charge Cooling sucks cause system is low
Car #2 is a modern Critical charge system, requires about 15Oz of R134, system was half full, you have overfilled the system. Symptoms are the same as a system that is low on gas (cycling clutch, very poor cooling) the difference here is the system is bouncing off the high pressure limit switch (450 PSI) but since you do not have a high pressure gauge you will never know this.
Car #3 is a properly charged system, fan across the condenser ambient temp about 70F
Car #4 is also properly charged, but the ambient temp is 80 and no fan across the condenser.
A few years ago my friends and I were at a festival and got caught in a downpour. By the time we got back to the car we were absolutely soaked. Sweatshirts, t-shirts, jeans etc. We hopped in the car, blasted the heater and the entire way home I had people bitching at me to turn the AC off. I finally got them to ignore it after I explained to them that the air from the vents is still coming out plenty warm, it was on recirculate and the AC being on is only going to help to dry the cabin air. It wasn’t much, but at least it would give them a small jump start on helping their clothes dry off (since it’ll act like a dehumidifier). I think they were too drunk to understand and at some point forgot about it.
But bringing fresh air into the cabin works just as well, or at least well enough in both the cool wet and very cold snowy climates I’ve lived in. And I’m a skier, so defogging the windows with a bunch of melting snow and sweaty bodies in the car is something I am very familiar with. The AC might work “orders of magnitude” better in some theoretical manner than plain old heat and fresh air, but the only practical difference is you get to start driving a minute or two sooner. My point was that it’s not as if the car won’t defrost in the winter if the OP doesn’t fix their AC.
Go back and read the part about summer in NY where the outside of the car fogged up due to the temp of the glass. You cannot tell me that the fogging on the outside of those windows was caused by a lack of heat or fresh air since it was 97 and all of the air in the State of New York was available. Don’t forget I was driving 35-40 at the time, so air flow was also not an issue. If the humidity (on either side of the glass) is high enough and the glass cold enough the defroster by itself won’t keep the windows clear.
Not theory, fact.
Sure I can. The issue was that the AC cooled your windows down to below the (dreadfully high) dew point. If you’d cranked the heater, it would have warmed the windows up and defogged them just fine, although you might have then died of heat stroke. Obviously in disgustingly humid and hot weather, AC is the only reasonable choice. But in the winter, you can safely and comfortably use the heater to raise the temperature of the windows above the dew point and it will defog them just fine, if not quite as fast as with AC and heat.
Dude seriously it is exactly the same scenario. One side of the glass warm and humid. the other side cold. The only difference between winter and summer is which side of the glass is hot and which side is cold.
Oh, BTW I loved this
But in the winter the cold side of the glass is the outside, so that means wait till April before you drive home from the ski weekend? :rolleyes:
That is true, though it hasn’t been stated in this thread. Leak testing is dependent upon detecting, in one way or another, refrigerant coming out of the system.
What I’m sorry to not see is your mentioning you “got” that the system has to be charged to test its performance. Forget for the moment about leakage, you simply can’t tell if the system works if it’s not full.
And, some leaks are very slow.
Yes. My experience is that if a system cools well for two years or more between top-up recharging, it’s very unlikely the leak is big enough to be found.
And, if the fan doesn’t blow cold air, there is either a leak in the system or the compressor died.
NO! Those are what we’ve been talking about because those are what you asked about in the OP, but those are only two out several possible reasons to not have cold air. It could have various electrical problems, a restriction in the system, or some other problem.
So my logical next step is to go buy one of these DIY kits, right?
Not necessarily. This is based on the assumption that the system is low, however we do not know that for a fact. You have the previous owner’s statement of what their mechanic said. How accurate is that info?
This was true for R-12 systems, but all cars made since the mid-90s have R-134a, and a number of earlier R-12 models were converted to R-134a. The sight glass you mention is NOT an indicator for R-134a systems.
I first check system pressures, sometimes it’s quite obvious that the system is low. In other cases I also need to measure the output air temperature to determine if that’s the case. It’s not quite as easy as it used to be.
Not at all. The window itself is a good enough temperature conductor that the inside and outside are fairly close to the same temperature. What happened in your example is that you cooled the window down, but also dehumidified the air inside the car. So even though the inner and outer surfaces of the window were approximately the same temperature, the dew point of the air touching the inside surface was lower, hence no dew. If you’d applied heat to the windows, eventually the temperature of the outside surface would have gone above the dew point, defogging it.
I might try buying a season pass and telling my wife this next year, but of course not. I’m confused about what you’re getting at here. Do you think it’s not accurate that the way a defogger works is by warming up the windows to above the dew point (and lowering the dew point if equipped with AC)? If not, how did they work in the dark days before AC?
::: Sigh::: You do realize you just made my argument for me, right? Let’s go through it line by line m’kay?
Exactly and in winter Jack frost is doing the cooling, and he has a shit pot more BTUs than you do.
NO shit! This is exactly what AC does, it removes water from the air. Summer or winter, it removes water from the air when it is running.
Exactly! Because the air was of a low enough humidity it did not condense on the inner surface. Same thing in winter. If the air is dry, no condensation, no AC moist air = condensation.
Yes a defroster works by heating up the window. This raises the temp of the windshield enough to keep condensation off of that piece of glass. However the defroster does nothing to warm all the other pieces of glass in the car. and keep condensation off of the inside of them. If the air in the car is warm and moist, and the glass (except for the windshield) is cold you will get condensation.
How did it work in the old days? Well back when I first started driving, integrated HVAC systems didn’t exist for cars. Neither did rear window defrosters. (at least not on the cars I drove) Frankly in the winter visibility sucked. All side windows and rear windows would be fogged. You would roll down your window to look left, or ask your passenger to roll down theirs to look right. Of if you were driving by yourself, you crossed your fingers, pointed it and punched it.
When I got my first car that had an integrated system, I did not know about AC use in the winter. I picked up my buddy one rainy day in the dead of winter. All the windows but the front were fogged up. The conversation went like this:
Him: How come you don’t have the AC on?
Me: Whaaaa?
Him: Turn it on, it will clear the windows
Me: Waaaa?
::: Switches on AC:::
::: 30 seconds later:::
Me: Holy shit I can see, all the windows are clear!
All I can say is either you have never driven a car with integrated AC, and you are unaware of what a dramatic effect it has.
Or
You have driven nothing but cars with integrated AC (which comes on automatically when defrost is selected)and you are unaware of what a dramatic effect it has.
Because nobody that has driven both types of cars would be making the arguments you have been making here.
How is this any different than a HVAC system that turns the AC on when set to “defrost”? It’s still only blowing warm (and/or dehumidified) air on one window (or three if it’s got those little side vents). Eventually all the air in the cabin of the car will warm up (and/or dehumidify) and it will then be safe to drive.
Baloney. If you waited the 5 minutes or so for the car to actually warm up inside, all the windows would thaw and clear and you could be on your way.
I’ve drive both on a regular basis (my truck doesn’t have AC, my wife’s car does) and hands down if you’ve got AC the car defogs faster. But I would seriously contest that it’s “orders of magnitude” better and a car without AC will eventually defog just fine-- you’re making it seem like driving a car without AC is like driving a car without seatbelts or windshield wipers or something.
I agree with greasy jack. Years ago I drove VW bugs or a Karman Giha, no AC. In cold weather I would start with all the windows fogged up, kept a towel in the car for the windshield. The windshield would start to defogg first. then the side windows and finally the rear window as the cab warmed up. The cars were not fresh air engines so the heater warmed up much faster.
Also the fastest way fo defog my pickup windows is to open the windows. But if I keep all windows closed and only take in fresh air from the vents and have the system in heat the cab will begin to fog up no matter how hot I keep it. I am putting out to much moisture, so I have to run the system in the defog mode.
WADR I believe you’re wrong about this.
My AC broke at the end of last summer and I didn’t bother fixing it until this summer. And the defog was completely non-functional all winter. (The fan worked, of course, but no defogging took place.)
It seems to be a pretty well established fact that AC dehumidifies air.
First, I’ve decided to pay a shop $80 to charge the AC system and do a dye test for leaks. It’s a shop I have dealt with intermittently for years and in my experience they’ve always been competent and honest.
Second - skirting much of the more technical talk upthread so this is merely anecdote - I have an old truck that hasn’t had working AC for about four years. I am in SE Michigan, it gets COLD here. The defroster with heat on clears all the cab windows of condensation and ice very quickly and keeps them clear.
Of course winter air is dry. During summer storms when it’s horribly muggy and rainy, the de-fogging windows function doesn’t work as efficiently without AC; I have to open a window or two. Especially if I have a passenger or a large dog or two in the truck, generating more humidity in the cab.
Was your heater broken too? Or do you live somewhere in California where winters are still too hot to use the heat?
I will concede that in climates where you have fogging issues at times of the year where using the heat is impractical, AC is very useful. But in places that have actual cold winters, the dehumidifying effect is mostly negligible because the heater will raise the temperature of the glass above dew point long before the AC will lower the dew point.