A/C pressure...

[xtremerevolution]

So in light of the last A/C recharge thread, my car's A/C decided to take a shit on me. I figured something HAD to break once the car rolled on 180,000 miles (which was officially 100 miles ago).

 

So I buy an A/C recharge kit, and it has a pressure meter there. 0-15 PSI is low (green), 25-45 PSI is filled (blue), 45-65 PSI is alert (yellow), and 65-200 PSI is WARNING (red).

 

I so I plug it into my car on the larger pipe with the lower connector to check the pressure as instructed on the canister, and what do you know, my pressure is sitting nicely at 120 PSI.

 

Prior to this, my A/C would turn on when I turned the car on, and after 10 or so minutes would just stop blowing cold air. If I turned the car off and turned it back on, the A/C would kick back on. Well the last time I tried that move, the A/C didn't kick back on.

 

Any ideas? That compressor better not have shorted out like it did last time. That was a $1000 job at the dealer.

[slick]

Wow, you paid $1000 to have a new compressor put on?

[MonteCarloDude]

Wow, you paid $1000 to have a new compressor put on?

[slick]

Anyways, did you try relieving pressure with the AC on the MAX setting?

[xtremerevolution]

Wow, you paid $1000 to have a new compressor put on?

 

My mom paid $1000 or so for the entire job when the A/C system got busted up, at the dealer. This was in 2003. Might have been closer to $850, since I don't remember exactly. Anyways, I need help with my problem, not with how much my mom paid the last time the system got fixed.

 

Anyways, did you try relieving pressure with the AC on the MAX setting?

 

Just letting pressure out of the system?

 

Why would the pressure be so high all of a sudden? I've never checked it before, but the A/C system worked just fine till a couple days ago.

[slick]

 

Anyways, did you try relieving pressure with the AC on the MAX setting?

 

Just letting pressure out of the system?

 

Yep, a flat or phillips head will let out some of the pressure. Had to do it on my Bonne. Let out a bit, then recheck the pressure.

[xtremerevolution]

 

Anyways, did you try relieving pressure with the AC on the MAX setting?

 

Just letting pressure out of the system?

 

Yep, a flat or phillips head will let out some of the pressure. Had to do it on my Bonne. Let out a bit, then recheck the pressure.

 

Ok, I'll walk outside and try that and get back to you guys.

[slick]

IIRC, possible reason for the high pressure is a failing or failed condensor. Someone correct me if I am mistaken.

[xtremerevolution]

IIRC, possible reason for the high pressure is a failing or failed condensor. Someone correct me if I am mistaken.

 

Hmm. what's the condensor, and where is it located?

 

Edit...I'm stupid. I googled it. That big radiator thing eh? How would something like that begin failing? Everything worked perfectly fine before the last couple of days.

[slick]

A lot of times, it's just sticks and leaves and whatnot stuck in the fins.

[xtremerevolution]

A lot of times, it's just sticks and leaves and whatnot stuck in the fins.

 

Well here's the next thing.

 

I decided to remove all pressure from the system and fill it up again with the recharge kit. So I did that up to the pressure that was recommended, and then turned the car off and turned it on again and went for a drive. It seemed like there was a relay in the engine constantly turning on and off every other second, and after a while, it stayed on and you could hear something going through the pipes when you put your ear close to the vents. From what I can tell, the compressor turned on right when I restarted the car and flipped on the A/C, which didn't happen before. However, there was no cold air coming through the vents. After a while, even the compressor wouldn't seem to turn on anymore.

[White93z34]

dumb question... but is the AC compressor clutch engaging? the middle of the AC compressor should not spin when the ac is off, and when it is on it will engage and spin with the serp belt.

 

from what you describe sounds similar to a failing AC clutch.

 

that relay noise you are hearing could well be the compressor clutch attempting to engage.

[xtremerevolution]

dumb question... but is the AC compressor clutch engaging? the middle of the AC compressor should not spin when the ac is off, and when it is on it will engage and spin with the serp belt.

 

from what you describe sounds similar to a failing AC clutch.

 

that relay noise you are hearing could well be the compressor clutch attempting to engage.

 

Hmm, that's not improbable.

 

As of now, the compressor doesn't attempt to turn on when I turn on the AC. This is what originally had happened, so I figured the pressure in the system was too low, so I bought the recharge kit. After finding it was too high, I lowered the pressure to the suggested levels, with no luck. I then released all the pressure and re-filled it to the recommended specs, and that's when I went out for a drive and noticed the relay constantly attempting to engage.

 

After a little while, it seemed that the compressor was on since I could hear the gasses going through the pipes while I was inside the car, but I felt no cold air. Upon restarting the car, absolutely nothing happens when you push the AC button. My speculation is that either something's broken, or the pressure in the system isn't right.

 

Now, the recharge kit tells you to set it to a certain level when the AC is on Max, presumably while the compressor is on. What would the pressure need to be if the compressor is off, since it won't turn on when I tell it to? Is this still an issue of the pressure level in the system?

 

I'm guessing the condenser is working fine since the system was blowing perfectly cold air right before it took a shit. Any ideas?

[xtremerevolution]

According to this thread:

 

http://forums.vwvortex.com/zerothread?id=3861402

 

The pressure in the system will be a lot higher when the A/C compressor is not running, and will drop once the compressor comes on. The problem is I can't get the compressor to kick on to start cycling the refrigerant because pushing the button doesn't do anything. Grr...

[digitaloutsider]

The pressure gauge you're using.. is it the one that comes attached to the can, or an actual high side/low side manifold gauge set?

 

Also, if you need to get the compressor to kick on, just jumper the terminals to the pressure switch.

[Russ]

If you just put a screw driver or anything to just release all the pressure in your A/C system at the schrader valve stem, then you cannot just put a recharge kit to it and get back to proper refridgerant running levels.

 

The compressor clutch starts engaging when it starts seeing proper pressures in the system, and going from atmosphere on upwards by adding can's isn't the way A/C works. You will have no A/C, or cold air blowing, or see the compressor's clutch engage until the system is done correctly.

 

Once you have released all the pressure, the only way to get your A/C properly working again is you have to have a vacuum pump draw the system back down to about 28 - 30 inches of vacuum, you do this with the middle (yellow) hose on an A/C gauge manifold set, then close the valve once it's pumped down, and switch the hose to freon cans, but before freon you should put the proper oils in, then you add freon cans until your reaching the proper pressures on the low side and high side gauges.

 

If you don't have this equipment you are going to have to have a shop redo your A/C system, this is why it costs people so much to get A/C fixed, plus the cost of freon and especially replacing the compressors, some of them cost over $500. retail depending on the car. So just a recharge can still knock you back a few hundred sometimes.

Good Luck.

[xtremerevolution]

The pressure gauge you're using.. is it the one that comes attached to the can' date=' or an actual high side/low side manifold gauge set?

 

Also, if you need to get the compressor to kick on, just jumper the terminals to the pressure switch.

[/quote']

 

Its the guage that comes attached to the can. I disconnected it from the can to use it more easily.

 

I'll probably do exactly that; just jump the terminal on the pressure switch to kick the compressor on to see what pressure there is in the system at that point. This thing hasn't been serviced in almost 6 years. If all it needs is more refrigerant, I'll buy another can and just feed it down till I get the right amount. If there's something else majorly wrong, I'll gut out the entire A/C system and use the Bonneville during the summer, since its only hot in Chicago 4 out of the 12 months of the year.

[White93z34]

I don't believe these cars have the oldschool pressure switch that older cars use, from what I recall there is a sender that tells the PCM that it sees proper pressure and to tell the compresser clutch to engage. shorting those pins together would most likely not be a good move since that goes to the PCM not the clutch.

 

what I would do.... get a multimeter on the OHM setting and remove the wiring connector from the compressor and check the compressor clutch coil with that. If it reads no connectivity, that would be a failed coil, If it reads way too high of resistance, it could also be failed. you could also atempt to apply 12v to the clutch directly and see if the clutch engages (with the car off!)

 

[xtremerevolution]

I don't believe these cars have the oldschool pressure switch that older cars use, from what I recall there is a sender that tells the PCM that it sees proper pressure and to tell the compresser clutch to engage. shorting those pins together would most likely not be a good move since that goes to the PCM not the clutch.

 

what I would do.... get a multimeter on the OHM setting and remove the wiring connector from the compressor and check the compressor clutch coil with that. If it reads no connectivity, that would be a failed coil, If it reads way too high of resistance, it could also be failed. you could also atempt to apply 12v to the clutch directly and see if the clutch engages (with the car off!)

 

 

How much would it cost me to take it to a shop and get the right levels back into the system? If its more than $100, the regal is staying parked on any day hotter than around 85 degrees until I get a pay raise.

 

I've got better things to spend my money on, like an engagement ring...

[White93z34]

no idea, but a set of manifold gages is only about $40 or so at most, that would give you a good idea of both the high side and low side. I would look into why the compressor is not engaging first and foremost, the AC system can run when it is prety darn low on freon so long as you actually have a cans worth (12oz ish) in the system it should engage.

[jeremy]

I don't believe these cars have the oldschool pressure switch that older cars use, from what I recall there is a sender that tells the PCM that it sees proper pressure and to tell the compresser clutch to engage. shorting those pins together would most likely not be a good move since that goes to the PCM not the clutch.

 

what I would do.... get a multimeter on the OHM setting and remove the wiring connector from the compressor and check the compressor clutch coil with that. If it reads no connectivity, that would be a failed coil, If it reads way too high of resistance, it could also be failed. you could also atempt to apply 12v to the clutch directly and see if the clutch engages (with the car off!)

 

 

How much would it cost me to take it to a shop and get the right levels back into the system? If its more than $100, the regal is staying parked on any day hotter than around 85 degrees until I get a pay raise.

 

I've got better things to spend my money on, like an engagement ring...

 

places around me advertise an A/C recharge for $30....not sure what it all includes though

[GutlessSupreme]

Almost definitely more than $100, because if you bring it a shop they're either going to:

a) do it the right way and charge for the labor and parts

do it half ass and charge you the same anyway

 

This is actually a very good walk through of how to do it properly.

http://www.honda-tech.com/zerothread?id=1665946

 

Russ is right though, the only way to properly refill it is to have it vacuum down first, then refilled with the correct oil and R134a. Once the system leaks and/or you release the refrigerant in the system (which is illegal btw), the pressure in the pipes is going to be 1 atmosphere (14.7 psi technically, but 0 psi are far as a pressure gauge is concerned) due to the air that is let in as the pressure balances with atmospheric pressure.

 

The refrigerant needs to be at a low pressure before entering the compressor so that it can be compressed to a higher density. 1 atm + the pressure from the refrigerant ≠ low pressure. The gas entering the compressor will be too dense to be compressed to the correct pressure.

 

Heat is added to the gas as it compressed to a high pressure by the compressor. The gas goes though the condensor which is basically like a big heatsink - it releases heat from the gas as the ambient air cools it. As heat energy is removed from the high pressure gas, it condenses into a high pressure liquid. The liquid goes through the orifice tube, which limits the amount of the hot liquid that is flowing through the tube. Limiting the amount of liquid lowers the pressure and temperature on the other side. The liquid then goes through the evaporator. The warm air coming from outside the car passes through the fins of the evaporator - since heat transfers from areas of hot to cold, evaporator absorbs the heat from the ambient air going into the cabin. The efficiency of removing heat from the incoming air depends on how cold (and surface area, etc) the liquid entering the evaporator is. It leaves the evaporator as a warm low pressure gas again, passing through the accumulator/drier to remove unevaporated liquid and drebris before entering the compressor again (can't compress liquid very well).

 

So essentially, if the gas on the low pressure side is at too high a pressure and density because of the air and moisture that's been let in, the compressor can't turn it into a high enough pressure gas to where it will be effictively cold later, because temperature depends on pressure, volume (which is fixed in a closed, unexpanding system), and density of the gas, and if it's not cold enough, then not a lot of heat can be absorbed before entering the cabin.

[xtremerevolution]

Damn, that looks like one hell of a job. How much will this cost me to get it done at a shop which has the proper tools? There's also the chance that the problem isn't just the pressure in the system.

 

I'm seriously considering just scrapping the A/C system and selling it off and using the Regal for the 9 months of the year that aren't blistering hot in Chicago, since it has 180,200 miles as of today. I'll just drive the Bonneville the rest of the time.

 

Oh yeah...WEIGHT REDUCTION!!!

 

Anyone in the market for a used air compressor?

[White93z34]

I don't see what is so hard about some basic diagnostics on the compressor before you scrap it all.

[xtremerevolution]

I don't see what is so hard about some basic diagnostics on the compressor before you scrap it all.

 

I'll run some diagnostics, but I'm not in the mood to spend money on this car right now when I only need AC 2.5 of the 12 months of the year in Chicago. I'll probably leave it in and if I can't get it fixed come September, its going up for sale.