Fix my AC

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Clement

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Mar 23, 2004
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Upstate, NY
1994 Merc Sable, 3.0L. Uses the r134 AC refrigerant. AC hasn't worked in a while. Last time it did, it wouldn't get very cold.

Went down to Advance Auto, bought a charging kit (bottle w/a pressure gauge), filled the system per the directions. The system had some pressure left, but not much.

Still no cold air.

The compressor may not be turning on?

Fuse? - I checked the fuses, couldn't find any that were blown.

What else should I look at?
 
About those recharge kits..Some people say they're great, other people say steer clear of them. I hear you'd need a gauge for the high pressure side and the low pressure side to properly charge an AC system, and from what I've been told most of those kits with the gauges only have one for the low pressure side (I think).
 
You should hear the compresor cycle. does the car have a sightglass on the reciever/dryer? Some do and allow you to see the presence of bubbles, indicating an underfilled condition.

Are you sure you put the right amount of refrigerant into the system? Is the pressure correct? Did you fill at the low pressure side?

You may have a massive leak, or there still isnt enough pressure. There is a high and low pressure sensor, and usually an evaporator temperature sensor too, all of which can cause the system to not work.

I run my ACs year round. We have never had any problems, even in 20 year old cars, as a result. Sometimes if the AC snt used enough, the seals will dry and crack, causing the system to not be able to hold pressure properly, resulting in it not working.

JMH
 
I can't hear the compressor cycle. If there is a sight glass, I don't know where it is.
I filled it up at the low pressure side with the engine running and the AC on full blast, per the bottle directions. According to the gauge, I raised the system pressure from about 12lbs pressure to about 40 pounds pressure. The red line on the gauge started at 45 lbs.

Would the problem show up as an odbc code? There is no check engine light.
 
A lot of 134a systems are pretty sensitive to over/under charged conditions and will not operate when a few ounces over/under charged.
 
I'd be suspicious of an electrical issue, living in the "salt belt" as you do. Make sure the compressor is actually getting power; it should have a power wire supplying 12V to operate the clutch, and a ground wire. If the connections are corroded, clean them up. With the engine off, you should be able to connect a jumper to the power connector on the compressor, touch it to the positive terminal on the battery, and see the clutch on the compressor engage.

Check also the connectors at the pressure switch (probably on the receiver/dryer). If it's a pressure issue, you should be able to connect a jumper between these two connectors with the engine running and the A/C turned on, and get the clutch on the compressor to engage.
 
quote:
Originally posted by 55:
About those recharge kits..Some people say they're great, other people say steer clear of them. I hear you'd need a gauge for the high pressure side and the low pressure side to properly charge an AC system, and from what I've been told most of those kits with the gauges only have one for the low pressure side (I think).
Click to expand...
Agreed... Ive used them before, and theyve worked well, but after a while, as the system gets used, they seem to need more adjusting. Like the pressures werent accurate enough or something.

Are you sure you filled in the low pressure side? Are you sure something screwey didnt occur? What is your pressure right now? All I know is my brother has a used car that he got the AC system charged on, and it wasnt cooling. I used a cheapo store gauge on the low pressure side(tested on other cars with working AC), and it read 75, yes 75 psi!

They fixed whatever they did and it has been frosty ever since.

So recheck the basics and take it from there. Id definitely have a shop put a good set of gauges on it and test it all out. May give you some good insight into the problem.

JMH
 
Are you positive the compressor was running while you filled the system? It' needs to be on to fill it or even check the pressures. Most likely you have air in the system and it never turned on when you tried charging it. It probably won't turn on until you get the whole thing vacummed out and profesionally charged. The system won't turn on when the pressure is too low or too high.
 
A/C systems don't consume refrigerent. If the charge is low, there's a leak and it needs to be corrected.

In addition, after a leak is corrected you'll have to replace the reciever dryer, replace any refrigerent oil, and evacuate the system down to about 29" of Hg to boil off any moisture in the system. (you may also need to replace the orifice valve and possibly flush the system if the compressor failed).

DIY A/C work is possible but is very exacting. You never indiscriminantly try and recharge a system without a clue as to what you're doing.

Start with the factory manual and test the system to determine what the likely root cause of the problem is. You'll generally need to know, low side and high side pressures, ambient temp and RH, and blower temp with fan on high after running for about 5 minutes.
 
Don't know if this rehashing an old topic, but has anyone used or know about product reviews for Interdynamics R-134a High Milage AC Booster? I understand about R-134 systems having exacting +- tolerances as well as ensuring you DO NOT add any type of sealant to your AC system. Just trying to make sure I don't cause any damage due to my ignorance. Thanks for any insight.

P.S. This is the 'magic stuff' I'm inquiring about.

-
 
quote:
Originally posted by Clement:
I can't hear the compressor cycle. If there is a sight glass, I don't know where it is.
I filled it up at the low pressure side with the engine running and the AC on full blast, per the bottle directions. According to the gauge, I raised the system pressure from about 12lbs pressure to about 40 pounds pressure. The red line on the gauge started at 45 lbs.

Click to expand...
Uh you must jump the low pressure switch in order to charge the system. 40 Psi with the compressor off is not enough!

The guage is meant to be read with the compressor turning.

The low pressure switch is on top of the reciever drier on the passenger side firewall. Unplug it and run a jumper wire between the 2 female connectors then start the car and turn the A/C on.

There is no sight glass on a sable. You must use a scale (preferred) or temperature and pressure guages (guessing game).

FWIW the orface tube is built into the liquid line and the whole line must be replaced after it's cut open to acess the tube.

The Taurus/Sable's have the worst A/C system ever made! Every connection uses spring locks and just acessing any A/C parts is an ordeal.

IMHO the days of recharging your A/C at home with a kit are gone forever.
 
Thanks Chris142

I put some more pressure in it last night, and the compressor turned on! It would only turn on for a second, then turn off for about five seconds. The pressure gauge was jumping between 25 when the compressor was cycling, and 65 when it was not cycling.

I'm thinking, therefore, I should hook the gauge up again and pump in more coolant until it reads about 45 with the compressor cycling?

I checked my Hyundai with the gauge and it read 45 with the compressor running, and it was well over 100 when the engine was shut off.

Chris is right, the design of this system sucks. The AC compressor is on the front of the engine under the power steering pump, right next to the front exaust manifold, and immediately behind the radiator, and also surrounded by AC, PS, and transmission fluid cooling and pressure lines.

I think the engine would have to be pulled or rotated in order to access the compressor.

I am NOT taking this thing to a garage for servicing.

Let me know if my idea above is a good one or not.
 
The 3.0 Vulcan is easy to get the compressor out of, the 3.8, and the later 3.0 DOHC are the ones that make you scratch your head.

Engine at 2000RPM, AC blower on high, airflow over the condenser, you should be running near 35psi on the low side. You really should have a high side gauge as well to catch any problems (orifice clog, bad compressor,plugged condenser). Just because your low side is correct, doesn't mean your high side is.

Chris142, you obviously know your stuff, but it is "orifice", not "orface".
 
So - I should fill the system until the gauge reads about 35psi while the compressor is running.

I'll look for a high side pressure gauge today too.

What should the high side gauge read?
 
This is one thing that's better to be done by a good techncian; seriously! I've seen more than 1 person screw up an automotive A/C system trying to get an accurate charge in a home garage. The gauges they sell at auto parts stores are a joke. You really need someone with accurate gauges and the know how to interpret the readings to get an accurate charge IMO. You probably won't even find a real high side gauge at Checker Auto parts.
 
Drew, I understand your point, but there is no way in He## I'm going to take this to a garage and spend $100 - $200 or more to have this looked at. Besides, the system is already screwed up, I'm just trying to fix it.

It's either going to work, or it won't. If it works, then Great! If I can't fix it, then it's no different from the way it has been, and nothing has been lost.
 
Start the engine with the AC off, then have somone in the car turn it on, you should hear a loud CLICK as the compresser clutch engages, the fans behind the radiator should also start up.

Let us know what u find here.
 
Monday I had started to fill the system, and after I added up to about 45 lbs, the compressor turned on. Previously the compressor wasn't running, I believe, due to a low pressure shutoff. After it started running, I noticed the pressure gauge would move down to 25psi when it turned on, and jump up to about 65 when it was off. I wasn't sure what to make of this.

Tuesday, I had figured that the pressure when the compressor was running was the important one, so I started pumping the stuff in. The compressor started running longer and longer, and the car started putting out cold air!

The compressor still shuts off when the pressure drops to 25 while it is running. I'll have to add more coolant to it.

I added one full bottle, 19oz bottle of InterDynamics stuff that had 3oz of oil in it and seal conditioners and stop leak and stuff.

All I have to do now is top it off and check the pressure a few times to make sure it isn't leaking.

Thanks!
 
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