Intermittent AC Cooling

[Gebo]

Originally Posted By: LeakySeals
You overfilled. Not filling according to ambient temp is a common mistake. Once it got hot out, there was too much pressure and the cooling became intermittent as the compressor cycled off. A few pokes on the low pressure schrader valve (when its hot, when its acting up) should resolve it.

ACPro temp chart


Thanks for the chart and input.

 

[LeakySeals]

No problem. You've been helpful to me on here, hopefully can return the favor.

 

[KrisZ]

These kit guages are pretty bad and get stuck quite often in my experience. Still, so far I successfully used them, although it was only a handful of times.

 

[Kestas]

Originally Posted By: Astro14
Originally Posted By: Kestas
Could the problem be with the automated climate control, and not with the underhood a/c system?

I'm having a similar problem with my 02 Volvo. When it's operating properly it cools fine.

For your Volvo:

Check the charge first (1KG I think).

Next, check your compressor clutch clearance. Should be about 20 thousandths. It can be re-clearanced if needed. Excess gap causes the clutch to disconnect when the compressor gets hot, leading to poor cooling.

If that’s not it, your car has a evaporator temperature sensor that cycles the compressor on/off. Faulty reading from that sensor will cause improper cooling - either too warm or the evaporator ices up.

Sensor is easy to get to, on the driver’s side. About $38 from TASCA Auto Parts

Thanks for the info.

I believe the problem may be related to the thermistor by the heater/evaporator cores. It flakes out in the winter, even after replacement, and I get the same problem heating as I do cooling.

My workaround is the set everything away from automatic - either full hot or full cold - and regulate the temperature with the fan speed, again away from automatic.

We have no more love for the car. It's been hit, has 200K, and we're limping it along until we inter it. Otherwise it runs great.

 

[Donald]

The reason why people should go to a A/C professional is they do not have the tools. The tools are not cheap once you get beyond a decent manifold gauge set. If you have to add refrigerant you have a leak. If there is nothing obvious it could be an o-ring or Schrader valve. To check for leaks you need a tool with a sensor wand. The leak detector additive is OK, but a tool with a sensor wand is better.

 

[JHZR2]

Go to a pro. There is no pretty please response.

- You added gas to a system without identifying the cause of leaks.
- You potentially overfilled a system that is illegal to release to the atmosphere.
- I am assuming you used pure r134a; if you used some questionable stuff which may have sealant or other junk, it may make your system UNRECOVERABLE (i.e. trash the car since a shop wont work on it), or at minimum, likely to clog and fail in the short term.

How much further should we go on?

The high pressure observed is odd. Im hoping you didnt overfill too much - being "in the green" could still mean you have too much in there. You really need to look at high and low sides. I wonder if you slugged some liquid in there, it heat soaked, and then the pressure spiked, but eventually it redistributed.

 

[Gebo]

Update:

Initial readings with Max AC, doors open, end of a 30 mile trip.

 

[Gebo]

After some hissing:

 

[Gebo]

Afte a little more hissing:

 

[Gebo]

According to LeakySeals' Chart at 85 degrees the low pressure should be between 45-55 psi and the high side should between 225-250 psi. Should I go a little lower or hang where I am?

It has run for 15 minutes and settled out at 50 and 250.

AC fan is acting properly. Belt looks good and tight. AC cabin filter was changed. Can I pressure wash the condenser or will it mash the fins over?

 

[JLTD]

Originally Posted By: Gebo
I'm wondering if that "[censored]" gauge gave me false readings and I overfilled it?


Easy to do, since the valves on the replacement refrigerant cans isn't high quality. I overfilled a couple in the past, let some out and it was good.

Hopefully you got the one with the dye so you could find the leak.

 

[Gebo]

Originally Posted By: JLTD
Originally Posted By: Gebo
I'm wondering if that "[censored]" gauge gave me false readings and I overfilled it?


Easy to do, since the valves on the replacement refrigerant cans isn't high quality. I overfilled a couple in the past, let some out and it was good.

Hopefully you got the one with the dye so you could find the leak.


No dye. Just wasted $20 on that craapy valve. Shoulda used my official manifold set. 20:20

I'm thinking it is just a leak from 12 years usage. Original owner said he never added any 134. Sorta like the peee down my 61 year old leg every now and then.

 

[sleddriver]

I'm puzzled about your order of operations. You have a nice gauge set but you did not use it? Why spend $$$ for something you don't need and is cheaply made vs. the real thing?

Having such a gauge set, it would be wise to measure hi/low pressures BEFORE adding anything. It would also be wise to measure both intake air and cooled vent air using a thermometer with MAX a/c set to OFF. With this information, you could then look up the P/T table to see what the pressure should be.

Next is the condenser coil clogged? Dirty? How about the cabin air filter? How about the evap coil? Since this isn't your DD, you don't know. (I once vac'd lots of moldy leaves from the unfiltered cabin air inlet of neighbors F150 who complained it barely cooled. Not only was the inlet clogged with leaves & twigs, so was the face of the evaporator. Furthermore the vacuum line controlling the RECIRC door was rotted. Thus no RECIRC).

Not sure why you would open the doors when testing....odd that.

A quick visual inspection of the suction line for sweat would also provide information. The blocked cabin air filter also restricted air through the evaporator coil which therefore could have gotten too cold which could have triggered the A/C compressor to cut out, resulting in barely cool air.

If you insist on DIY'ing this, you need to go about it methodically. You also need to understand there is more to auto A/C than simply adding a can of gas.

Thus the refrain of "Don't touch it unless you know what you're doing".

 

[Gebo]

I thought I had given my good gauges to someone and had forgotten about it. Believe me, I’m a little slow but I wouldn’t have purchased the $20 hose if I had known the good gauges were hiding in my basement.

The doors were left open to keep the AC running full time.

How do the pressures look to you?

 

[JHZR2]

Originally Posted By: Gebo
Afte a little more hissing:




So you let gas out, which is a clear violation of the clean air act?

Quote:
Section 608 of the Clean Air Act prohibits the intentional release (venting) of any refrigerant when maintaining, servicing, repairing, or disposing of air conditioning or refrigeration equipment, including MVAC systems.


This can't go on.