Well I took my other low mileage ‘05 MCS for a drive today and ran the ac but it never got cold or cool for that matter. Is there anything special I need to know about these cars for the ac system or basically the same as any other car?

 

nothing special about the a/c system other than parts being fairly unique to the car/make (like any other car)

any a/c place can check your pressures and look for leaks . . .

for an 05 to need 'gas' would not be unusual ...... the best thing you can do for an a/c system is have the gas checked annually ....... keep it topped off and know about leaks EARLY.

Even with home systems .....

p.s. check your coolant tank ...... if the car is having issues with keeping the engine temp in line it can stop the a/c from running . . .. wanna guess how I learned this one?

 

One issue I have read about is that the compressor clutch electromagnet is a common failure point. I would check to see if it is engaging and if not, it would be a good idea to put a test light on the single black wire that energizes it. Sadly, it is hard to get to without the car being in at least a partial service mode so you can reach your hand up and disconnect it. On mine the insulation had all peeled off the wire due to the effects of time and heat on the insulation. I got lucky and it still worked ( I insulated it with liquid electrical tape) but can see it shorting or corroding to the point of failure if left unchecked.

Now, if the compressor is coming on, then it is time to check the system with your manifold and gauges. If it is not, and you have sufficient refrigerant in it, then the issue could be electronic. In that case, work your way backwards through the circuit starting at the compressor clutch and see where it has signal. Check the relay, but check the wiring from the clutch to the relay with your DVOM. Also, while you are at the relay, test for ground as well as a 5 volt relay energizing signal. Why not 12 volt? Most automotive computer systems use a 5 volt output to run a 12 volt circuit by a relay so that the logic boards are not driving heavy loads.

 

Wow thanks for the info, I will definitely check all of that.

 

Mine is cold/not cold.
Mine is a simple leak. I can fill the system with a cheap (!?) store bought refrigerant can and filler hose. It then works great. Only problem, it only works for a little over a day before it blows ambient air again.
I haven't seen any "obvious" wet areas on the hoses, but then, most of their length is hidden by other stuff.

I'll be changing the oil in the next couple of weeks so I'll be under the car...will look harder then.

That's my non-working air conditioning system story.

Mike

 

The next time you put your days worth of refrigerant in it, use a can with UV tracer dye in it. That way, you can see where it is leaking. Alternately, you can use a halogen gas leak detector, but they tend to be quite expensive. If you can get one, remember that you use it the same way you use a geiger counter to detect ionizing radiation and do a slow sweep to try to pinpoint the leak. You also want to put the tip about 3 inches above the registers in the center of the dash about 2 to 3 inches after the registers. This way, the gases will hit it and it will not give a false reading from being in the air flow. This should be done on a low fan speed setting too. The reason to do this is that it is the only way to find an evaporator core or TXV leak without disassembly. (I'm not a professional HVAC guy, but I have learned from friends who are in the business and now know just enough to be dangerous!)

 

Blue -

Thanks for the tips.
The dye sounds like good plan, the Halogen seems (by what you say) more than I'd spend.
I'm OLD (retired), and this is only my second air conditioned car. So while uncomfortable, I can live with opening the windows if the fix costs too much. I'd rather spend the money on making more power or better handling, even at my advanced age..!

Mike

 

Ok, I did not read the other replies, so I hope this is not redundant.
The clutch magent is a common issue and can be replaced by itself. If the system is low on R134a, then you should replace the dryer tank, or at least vacuum down the system for a few hours. Make sure not to over fill it, by only putting in what the system calls for. None of this cost too much! There is a chance the compressor is bad and that is about $400.
I never recommend putting any contaminants in the system, like dyes, stop leak, or anything other than R143a and the proper oil. These all contribute to lesser cooling from the system.

 

Thanks what about AC Pro that you can buy at the auto parts where u just hook it up and squeeze the trigger?

 

alconk -

That's what I used to top off my system. The hose and gauge are very handy, though not sure how accurate the gauge is.
On the good/safe side, these cans don't have enough pressure to, over-pressure the cars system. At least the one I used didn't.
Be sure to follow the instructions. Just connecting it won't get you a proper fill.

Mike

 

It is fine to use that, but I would not want the one with stop leak in it. Also, if it is out of fluid, you will need to vacuum it down, or moisture inside the system, will freeze and stop it from cooling. (if it is not totally out of pressure, it may be able to just take a better charge.
Remember this: only proper oil and R143a should be used in it.

 

I agree with not using stop leak as it is only a temporary solution at best and will cause chaos when you go to disassemble the system and fix it properly. The dye is not that bad when used in small doses and I have used it in a number of older cars with good results. I do agree that it is sub-optimal though. It all depends on the person's budget. Most of my life has been spent on a low income of less than $30k a year and most of the cars I fix for others have been for people making even less than I do. For that reason, I am willing to make do with a little less perfection when the practical reality demands it. I have fixed the A/C systems in many a beater for under $100 in parts and materials using things like $40 used junkyard compressors and $10 eBay driers to make the repair affordable for the person I was trying to help. Most of them were poor enough that I didn't charge for my time since I enjoyed being able to help others and that was payment enough for me. In some of these situations, a $200 repair bill for A/C would have been too expensive and their families would have had to go without during the harsh, Florida summer.

I do agree with vacuuming the system. I have my own vacuum pump ($80 on eBay) and a set of gauges ($40 at Harbor Freight) and use it any time a system has completely lost pressure. The only time you can get away with it is if the system has a slow leak and never loses positive pressure. Any time you open the system you should replace the drier as it acts as a filter and dessicant in the system. I also buy a vehicle specific O ring set from Rock Auto for the cars I do as it is usually under $10 and saves a lot of hassle. For refrigerant, I buy that at Wal Mart for $5 a can. The A/C Pro stuff is a lot of overpriced marketing hype and not worth the cost, IMHO. The gauge it comes with is crap, and you are much better served buying a setup at Harbor Freight like I did and learning how to use it properly. I was taught by a certified A/C tech I am friends with, but there are videos on YouTube that can teach you just as easily.

BTW, I found my leak detector at a half off sale at a Goodwill and only paid $5 for it. It was a lucky find as I later found the same one at a pawn shop for $80! I buy a lot of beat up looking, functional tools on the used market from garage sales, thrift stores, flea markets, pawn shops and Craigslist. I am too poor to worry about cosmetics...

 

Wow that’s a lot of information and I thank you for that. I still haven’t had a chance yet to see if the compressor is coming on but will try tomorrow.

 

Ok compressor is on and is not cycling on and off like if there was a low charge but there is a weird noise coming from down behind the dash around the pedals under that cover. Sounds like a flowing sound with a hiss and is sold. Goes away when turned off and comes back when turned on??

 

Ok I take back my previous statement. The power steering fan is on the compressor is engaged but the tad fan is not running. I hooked up one of those ac pros with the gauge and it was right in the middle of the green so my guess is the fan is the culprit just got to figure out why??

 

Well if anyone would know I have a PowerProbe III and I disconnected the plug to the fan and was able to run the fan but only a short time and it would trip the breaker in the Power Probe and that is with the AC on. With the AC off I ran the fan for a long time and it never tripped the breaker??? I was not able to operate the low speed on the fan though. Could this be due to a bad fan resistor?

 

Yes, if the slow speed is not working 98% of the time it is a bad resistor.

left is OEM right is aftermarket

 

Ok why isn’t the high speed kicking on with the ac? Or is the low speed that comes on with the ac?

 

The low speed comes on when the ac is on and then when the temp goes up, the high speed kicks in. If the low speed is dead, the high speed does not come on until the high temp switch, kicks it on.

 

Ok thank you for verifying that. So that's why the AC isn't working. I have a new fan and resistor coming.

 

No, the AC should work anyway. R53s are known to have compressor clutch failure, but make sure the fuse is not blown and that it has enough R134a to trigger the compressor on. If there is not enough initial pressure (50Lbs) in the system, it will not come on.

 

The clutch is engaged and my pressure is good but the condenser gets extremely hot unless I jump the high speed fan then it starts to cool down until the 50 amp draw trips the breaker in my Power Probe.

 

It sounds like the fan motor is EOL (end of life)
I am sure it also needs a fan speed controller.

 

I took the fan out today and looked at the resistor ( was disintegrating in my hand) everything else is good.

 

Well I replaced the fan today and now works like it should but still no AC?? The AC clutch is engaged, pressures are good but not cooling, weird... I do hear what sounds like high pressure in the interior under the dash though?? Could the high pressure switch cause this or would it kick out the ac clutch? I don't know what else to look at.