Engine Size: 2.2l
Refrigerant Type: R134A
Ambient Temp: 75
Pressure Low: 30
Pressure High: 40
Country of Origin: United States
I recently bought a 2002 Vue that turned out to be a great deal on a solid vehicle, but I need to get the A/C working again to get it into pristine condition. I knew the A/C hadn't worked for several years because the former owner is a friend of mine.
I haven't begun any repairs yet, but thus far I'm thinking of replacing the compressor, dryer, and expansion valve based on my assumption that the compressor is on its way out.
What I need help with is interpreting what these "symptoms" mean and if replacing the above parts (after having the system evacuated, the following with a flush/vacuum/recharge) will likely result in cold A/C or if further work should be done.
1) When I push the A/C button, the compressor does cycle on. However, if I do this while driving, it will frequently cause the engine to stall when coming to a stop sign. (This is what leads me to believe either the clutch or compressor is not healthy).
2) When I do spend any amount of time testing the A/C with the clutch engaged, when in return to the car the passenger floorboard is wet. I read that this is often due to the firewall drain being clogged, but I put a pencil in mine and could not feel any obstructions.
3) Using a UV test kit, I've tracked my leak down to what some parts diagrams refer to as a relief valve. On this car there is only one connection on the compressor where both hoses go in. At the bottom of that block / bracket there is the relief valve. The UV kit shows that the leak originates around that valve, although there's a good deal of dye around the compressor itself as we'll.
Thank you in advance for any advice/input.
You have already identified a leak source. IMO, I'd evac & charge the system, then run it to see if it can pump up the high side pressures. If so, and the compressor isn't making a bunch of noise, then replacement is unnecessary IMO. To be doubly sure, you could remove the compressor drive belt and verify the compressor turns freely (not just the clutch, which will freewheel).
If it turns out that the compressor HAS undergone catastrophic failure (excessive noise, hard to turn, et), then a complete flush of all the lines and replacement of the condenser is in order if you want the replacement compressor to last.
Thanks for the response!
I'd certainly prefer to avoid replacing components if not necessary. Is the stalling issue not indicative that the compressor is going out?
And does the condensation that collects in the passenger floorboard reveal anything?
I just came up with a theory for your stalling issue. It could be right or wrong, might not even be possible, but here it is. Your pressure readings are low, for the theory, lets say your low pressure cut out switch is not stopping the compressor when the pressure get too low and there is little to no freon flowing. Not a big deal except this also means no oil is flowing though the compressor. The compressor gets hot and starts to seize due to the lack of oil. Sound good to anyone?
As far as the condensation on the floor board, where did you put the pencil checking for an obstruction? When I have seen this problem, the plug has always been inside the housing where the evaporator is. It gets some dust and dirt inside, and a little water, turns to mud, hardens and plugs the drain tube. I assume this happens a few time and eventually the plug is large enough that adding more water to the top of it does not soften the "mud" enough to let the water get past it. if the drain tube can be pulled from inside the passenger compartment, take it off and see if you can find a plug. The evap. housing may not have to be pulled to solve this problem, but should be pulled and cleaned out. Silly question, any chance this condensation is antifreeze? A wet floorboard is often a sign of a leaking heater core.
I bought a can of 134a at w**-mart that had a stop leak, oil, and dye in it. It also had a hose and a gauge, so now I'm an AC pro!
It's definitely water - I don't lose any antifreeze and it only occurs when the compressor is engaged.
I could have been wrong, but I swore it was colder than ambient temperature last time I felt it.
I try to limit the amount of testing I do with the compressor running since it can't be good for the system.
I put the pencil in the drain tube on the firewall. On this vehicle the dash needs to come out to get to the evaporator so I really hope to avoid that.
Re stalling issue: A hard-to-turn compressor definitely adds excessive load to the engine. However, I'd expect it to cause idling problems under all conditions, not just coming up to a stop. It sounds so borderline to me that while it MIGHT be a heavy compressor load, it could just as easily be an issue elsewhere in the engine (marginally dirty idle air control valve, etc - any codes?).
Well, the thing is the car never stalls unless the A/C clutch is engaged.
My scanner doesn't pull any OBD trouble codes and other than the A/C the car runs like a champ.
I'm thinking I'll go ahead and buy a new hose & relief valve, evacuate and vacuum the system, then recharge and see where that gets me.
If something else still needs replacing, I'm only out the cost of having the system evacuated an extra time and the cost of the refrigerant.
Since you want to minimize the number of times you have to evac/charge, pull the belt off the pulley and see how hard it is to turn the compressor. It does sound like your compressor might be shot. If it's hard to turn, then in addition to a new compressor, make sure you budget for a new condenser as well. Do all this before you have it recharged to minimize the liklihood of needing additional evac/recharge cycles.
Thanks, webbch. I didn't think to try spinning the compressor by hand.
Unfortunately it turned, but was quite "grabby" - meaning I would have to exert a decent amount of force to get the compressor to turn, then when I reduced the amount of force I was applying it would grab and stop turning.
From what I have read elsewhere I was originally thinking if I needed to replace the compressor I would be changing the expansion valve and drier/accumulator at the same time, as well as flushing the lines, condenser and evaporator. You're saying I should actually replace the condenser as well? Will flushing not remove any contaminants from it?
Thanks, HECAT! This forum rocks.
I have to take the car to a pro to have the system evacuated (it does show some pressure still) so I'll see if they can flush the condenser & evaporator at the same time. The two-line assembly on this car from the compressor to the condenser & return line is one piece that I plan on replacing. The only other line from the condenser to the expansion valve is included with the accumulator assembly. That leaves only the condenser & evaporator to be flushed and every other piece is going to be replaced.
I have a theory about what went wrong with my system - something inside the compressor failed, resulting in the system over-pressurizing and releasing through the valve where I discovered the heavy leak. Sound plausible?
Very plausible; but there are a lot of other plausible possibilities as to why it has been non functioning for years. If leak sealers were added, or the condenser fans or air path were compromised; the system could have been over pressurized and thus contributed to the compressor failure. Regardless, a complete system overhaul is in order.
Part of your suggested repair sound feasible...other parts are not. Unfortunately this vehicle may need additional parts replacement. A suggestion would be to replace the condenser. The evaporator maybe able to be flushed and cleaned...be sure to inquire as to what chemical the shop prefers.....post this info...it may not be an acceptable chemical. However, the condenser is another matter....it is highly unlikely the shop will have the necessary and proper equipment to adequately clean this condenser. Even so, the cost of chemicals and labor may be similar to the cost of a replacement. Even if the unit is flushed...how do you know for sure it is a valid condenser and does not still remain restricted. The evidence of the PRV (pop off valve) leaking is typically an indication of a restricted condenser. The flow patterns of this unit will prevent proper cleaning. Keep in mind a restriction within the system will result in premature compressor failure due to lack of sufficient lubricant migration.
By all means have the system professional recharged....this system requires only 24 oz of refrigerant....very easy to undercharge this system utilizing cans. 7 oz of PAG 46. No more than 2 oz in the compressor. None in the condenser.....put in in the evaporator. Once lubricant is added to the compressor...reinstall the port covers and stand the compressor upright on the driver (front of compressor) for several minutes. The front of this compressor has numerous bearings and these need to be lubricated prior to start up. Just a bit of insurance.
Be sure to check the electric fans...they could also cause the PRV release.
Good luck with your repair.
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Many vehicles have an "idle-up" circuit to raise the rpm when the AC is on, to prevent stalling.
Or they have a "stall-saver" which disengages the compressor if engine rpm drops too low...to eliminate the threat of a stall..on a tight compressor.
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......
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