Alright. Families 2002 Mercury villager's a/c hasnt been working for a while. Today I said Ill give a go at it and try to fix it. So I got some refrigerent and a pressure gauge, started the car, a/c on and looked at the refrigerent pressure. It read low so I pumped it up to 45 psi. The a/c was still blowing hot. I took a reading again and the gauge cycled from 25 psi to 45 psi. I looked at what I think is the compressor clutch pulley, and it was not spinning. We took it for a drive and with the A/C on there was a cycling noise, on and off of some component or motor. It sounded like the compressor turning on and of but I'm not sure. When it went on the lights went a little dimmer, so I'm assuming something was drawing power from the alternator and battery. Is this an electrical problem? Is there a fuse or sensor I should check? The hazard light fuse was replaced about a week ago, and the speedometer glitched out a couple of times on the highway. I replaced the hazard light fuse, but is there a another fuse box on the battery? Or do I need a new clutch/compressor? If someone could point me in the right direction, I would much appreciate it before I rip into anything. Thanx =)
A/C Problem
- Thread starter rangerfan24
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anyone ?=/
Jump the compressor clutch directly to 12V and see if it engages. If it doesn't, you have a faulty clutch. If it engages, throw on your gauges again and see what pressures you are getting.
The compressor is supposed to cycle. This is normal and good.
You only check the low side pressure when the compressor is engaged, otherwise it is meaningless.
45 is too high unless it is VERY hot out. Like 110 deg F or so ambient temps.
You only check the low side pressure when the compressor is engaged, otherwise it is meaningless.
45 is too high unless it is VERY hot out. Like 110 deg F or so ambient temps.
The compressor would cycle every 5 seconds. Is this still normal? And i checked the low side, and I believe the clutch was NOT engaged when I raised it to 45. It was very hot out, about 90, and the bottle said to go to 40. How would I jump the clutch, and also its not going to explode or anything after the clutch engages with the pressure being 45 correct? Thanks. Info much appreciated =)
Ok. Poked around the internet. It seems I just pull the under hood fuse box cover, pull the relax box for the ac and and stick a paper clip between the two ports while wearing gloves or some electric tape to keep from shocking myself. My question is. it sounds like the compressor is on, so wouldnt the clutch have to be engaged for the compressor to run? Or am I mistaking the sound for something else? Thanks chrome and mech 2. You've gotten me a little farther.
Aight the clutch wont engage. Im gonna guess its the low pressure switch cutting it off. Is it safe to exceed 45 psi until the clutch clicks on and brings it back down? Or should i have someone jump it while I add refrigerant. I'm a little confused about how to go about jumping it. and still don't under stand the quick cycles it had the other day. Maybe the jumping from 25 to 45 was the switch kicking in? Maybe 25 isnt enough to sustain the compressor? If I add more then when it cycles off pressure will exceed 45. Is this okay? As long as Im not going to blow my young teenager self to smitherines I'll give it ago. [censored] these DIY genes I got from mom...
Sure, 45 when the clutch is not engaged can be normal.
Actually, at rest when cold, the low and high side equalize, and are at about 80.
So it seems that your system actually is at 25, which is probably a bit low. It varies, but shoot for 30 right now.
You should have enough to allow operation. Both the high and low pressure switches should be in the normal range at this point.
Actually, at rest when cold, the low and high side equalize, and are at about 80.
So it seems that your system actually is at 25, which is probably a bit low. It varies, but shoot for 30 right now.
You should have enough to allow operation. Both the high and low pressure switches should be in the normal range at this point.
Ok. Compressor engages, compressor turn fine. Still hot air. Am I missing something?Thanks mech. Youve gotten me pretty [censored] far.
What was your low side pressure with the compressor continuously engaged?
25, then it would shut off.Do you think there is a leak in the system after the compressor, hence no cold air? Should I add another can? Thanks guys.
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25 then shutting off is normal. What is your high side pressures? you need to look at both before figuring the system out. Follow the small tube out the compressor, through the condenser, and to the expansion valve. At the valve (or tube), the "in' pipe should be warm, the larger 'out' pipe should be cool. if it is not, then there is your issue. If it is an expansion valve, it probably needs to be replaced. If it is a tube, you can usually open the system, remove and clean/replace the tube, then vacuum and recharge the system.
Alright ill try to find this expansion valve tomorrow morning. Small tube out of the compressor. Will the condenser be near the radiator? Im frustrated, but at least I'm learning. Now the vehicle does have an a/c in the back. What components would be in this? Thanks for all the help.
Are there two expansion valves, a front and a rear?
Theres a pipe leading into the condenser, then one leading out. The one leading out was FRIGID, perfect, but the air is still blowing warm. any ideas? Man, I think the A/C is the most complicated thing to diagnose on modern vehicles. Thanks again. =/
There are tubes leading to the rear of the car. Im assuming thise is for the rear ac. Is the evaportor located in the dash or under some panel in the back? it felt cool for a little while. Not cold, but cool.
Ok. lol I got the rear cold. Nice and cool. Front is still warm. Any ideas now? I might as well open an ac repair shop by now.
Sounds like it might be a problem with the blend door (or whatever system Mercury/Nissan used to supply hot air to the cabin). In a nutshell, most cars have some sort of door that opens or closes to allow airflow over the heater core and then allow that air into the cabin. Maybe yours is stuck open, and is thus heating the air that the evaporator has already cooled down.
Some cars also have a valve in the engine bay that opens or closes to allow hot coolant into the heater core - I once had a 1992 Nissan Maxima that had this type of system. If your Mercury uses this sytem, could be the valve is wonky, or the cable that adjusts the valve has come off, thus allowing hot coolant to always flow to the heater core, and giving you hot air.
I'm only thinking along these lines because you say the rear A/C is working, and the compressor is running and the low pressure line at the condenser is cold.
There are probably two evaporators for your vehicle, one in the rear somewhere and one under the dash for the front.
By the way, the cold line is actually gaseous refrigerant returning from the evaporator to the compressor where it then gets compressed (and thus heats up). From there it runs to the condenser (at the front of the vehicle before the rad) where it gives up some heat and turns from a gas into a liquid. The expansion valve then meters this liquid into the evaporator, where it turns into a gas again as it loses pressure at the same time turning cold and absorbing the heat (the heat is actually being transferred) from the cabin as air flows over the evaporator.
Some cars also have a valve in the engine bay that opens or closes to allow hot coolant into the heater core - I once had a 1992 Nissan Maxima that had this type of system. If your Mercury uses this sytem, could be the valve is wonky, or the cable that adjusts the valve has come off, thus allowing hot coolant to always flow to the heater core, and giving you hot air.
I'm only thinking along these lines because you say the rear A/C is working, and the compressor is running and the low pressure line at the condenser is cold.
There are probably two evaporators for your vehicle, one in the rear somewhere and one under the dash for the front.
By the way, the cold line is actually gaseous refrigerant returning from the evaporator to the compressor where it then gets compressed (and thus heats up). From there it runs to the condenser (at the front of the vehicle before the rad) where it gives up some heat and turns from a gas into a liquid. The expansion valve then meters this liquid into the evaporator, where it turns into a gas again as it loses pressure at the same time turning cold and absorbing the heat (the heat is actually being transferred) from the cabin as air flows over the evaporator.
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Alright. Im gonna call the dealer and ask about this blend door, actuator and orfice tubes. They gave my dad some [censored] how the lines running to the rear always rot. I looked under the car they're sealed in plastic, no breaks so thats out of the equation. Thanks.
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