VetteMed

The AC system is giving me fits. I've got a new compressor/condensor/evaporator/accumulator/orifice tube. I added 3 oz of mineral oil to the evap, 2.5 to the accumulator, 1 to the condenser, and around 3 to the compressor. I evacuated the system down to 29.9mm Hg, then added 36 oz of R12 (the factory spec).

Cooling is nonexistent, the system cycles very rapidly, every 3-4 seconds, the low side gets cold but the evap fins do not get cold and therefore the air does not get cold. I disassembled the system today and found over 8 oz of oil in the evaporator, hardly anything in the other components. WTF is going on??


EDIT: As of July 7, 2011, the manufacturer and the vendor have become difficult to deal with in an effort to get a refund or replacement for an evaporator that was built defectively. Vista-Pro is the manufacturer, and Air-Parts (in Arlington, TX) is the vendor, I would caution everyone to avoid buying parts from these companies as obviously quality control is not a priority.

383vett

Attach a pressure gauge to the low pressure side and see why the system cycles off. It's either too much or too little pressure. The gauge will tell you what. As far as the oil, someone else might be able to answer that.

myk7

I've read your other post and I have some questions about the filter you put in. Where did you put it and which way is the arrow pointing (I'm assuming it has an arrow). That filter is the only thing that's not really supposed to be there, so that's the first thing I would look at. I'm thinking it's putting weird pressures in your system and moving oil around.

When you say the suction line is cold, are you talking about the one going into the accumulator, the one going to the evaporator, or the one going to the compressor? Are the lines cold anywhere else? What are the high side and low side pressures?

VetteMed

The filter is in the high side line, between the output of the condenser and the orifice tube / input of the evaporator. There is an arrow on the filter body, indicating the direction of flow. It is facing in the correct direction. I will go out to the garage in a minute to inspect the screen inside the filter for any debris.

The suction line is cold, all the way from the evap outlet, thru the accumulator, and back to the intake of the compressor.

The low side pressures would pull down to about 23-25, the compressor cycled off, then went up to about 50, where the comp turned back on again.

High side was hovering around 200 or so from what I recall.

Thanks
Andrew

myk7

I think that filter is supposed to go in before the condenser while the freon is still hot and less apt to change to gas. Is the line getting cooler right after the filter, towards the orifice tube? Is it cool at all right after the orifice tube, on the way to the evaporator?

VetteMed

Hmm, interesting. I will go dig up the instructions for the filter. I do not think the line was getting especially cold after the orifice tube, now that you mention it. It only seemed to get cold after the condenser.

EDIT: only got cold AFTER THE EVAPORATOR. The liquid line was never cold.

VetteMed

From the instructions:

"Installation of the filter should be between the compressor discharge and the R/D on a TXV system, the orifice on the CCOT, and the TXV/Orifice on a dual system".

"The purpose of the filter is to minimize contamination to the TXV or orifice. Therefore, it is generally recommended to install the filter after the condenser."


This is the filter: https://www.ackits.com/pc/13128TSI/i...In-Line+Filter

I just checked the screen, there were a couple of *TINY* particles on the screen, but nothing that I think would present any significant reduction in flow.

myk7

Hmmm.. It should still be hot after the condenser, it shouldn't get cold till after the orifice tube (when it changes to gas). Should stay cool/cold till the compressor, then hot coming out of the compressor and on to the condenser where it gets cooled, but not cold.

VetteMed

That was a typo - the liquid line is not cold at all. I meant to say it doesn't get cold until after the evaporator.

myk7

So, it's still hot right after the orifce tube? Did you put the oil back where it's supposed be and recharge the system today?

VetteMed

It did still feel warm to me after the orifice tube, when I felt it. However, I have the system all torn down right now because I wanted to see just how much oil was in each component. I'm worried I'm going to put it all back together and have the same result.

yorkfitter

I do AC for a living. It sounds like it could be an air flow problem, are u sure that the dampers are open for the evap or something is not blocked. If there was a restriction the suction line would not be getting cold and the discharge pressure would be higher. The discharge line should be hot and the liquid line after the condenser should be warm, but this will depend on the outside tempreture. If it is hot outside you probaly cant touch the line off the compressor, but the line after the condenser should be warm.

VetteMed

It was over 90 degrees today - the discharge from the compressor was warm, but not burn-your-hand hot.

I have already verified visually that the blend door is functioning properly - the evaporator core is just not getting cold. My first thought was a blend problem, letting in hot heater core air mix with the cold evaporator air, but no luck there.

Thanks for the input.

myk7

Sounds to me like there is a partial blockage in the evaporator, backing up the orifice tube and only getting cold after the partial blockage, too late to cool the car. The oil problem is still a mystery to me, assuming the pressures are correct... unless the partial blockage is keeping the oil in the evap.. that would explain the low low-side pressure, but the high side pressure would be much higher.

VetteMed

At this point I'm OK with ordering a new evaporator, I just want this thing fixed already. The evap was new as of last year, and never run, but it's an aftermarket part, so who really knows what the quality control is like...

myk7

I'd shoot some air through the evaporator to see if air flows easily through it.

VetteMed

ya know, I did shoot some air through it earlier, and I have to say, it didn't seem like it came out as forcefully as it went in. I think I'm going to cut that evaporator in half and take a peek in each plate/fin.

VetteMed

Ok, get this... I cut the evaporator in half, perpendicular to the plates. I ran water into the outlet fitting of the evap, and water came out of all plates evenly. However, when I ran water into the inlet side of the evap, only the plates at one end had water coming out of them. Sounds pretty diagnostic for a blocked evaporator, which would explain a lot. With that blockage, the pressure in the evap would not have dropped very low, and of course the plates would not get cold, and therefore no cold airflow.

I will cut the evap open further tomorrow - but at least it seems that we've gotten to the bottom of this - thanks myk7 so much for pushing me in the right direction!

Andrew

VetteMed

Also thanks Yorkfitter for the mention of the restriction in the system!

myk7

Wow, you don't mess around.. heheh

I thought you were going to pull it this weekend or something. Sure sounds like you found the problem.