AC Problems..... Please help

[tandb]

I recently paid to have paid to have my system converted to r134a cause my ac was blowing warm air. After the conversion I still had warm air. The mechanic told me it my be my blender doors. After a little troubleshooting myself I've found my low side is ice cold(by the valve), I also found its cold by the expansion valve inside the AC unit, but then after that there is no coldness in the system.

My mechanic friend told me if I clamp the hoses by the firewall for the heater core that it would cut off the heater core and the air should go cold and that that would let me know if it was a blender door stuck or inop. I tried this and the air stays warm.

I'm leaning at a bad expansion valve but my friend told me if I had a bad EV that I would abnormal high and low pressures but the place that converted my system said my high and low pressures were good.

So please if someone could help it would be great cause Georgia is getting really hot right now... Thanks in advance.

[Ziggy1621]

Welcome to Nico. I don't know that I've encountered this issue yet so I'm curious to see who can chime in. Does anything change if you go to defrost/foot?

[tandb]

Air transfer happens the way its suppose to and always comes out the right vents. Just no cold air.

[nissanfreak12]

Is the air at least cool?

Does it change when you drive it?

Did the tech tell you the readings? WHat was the outside temp at the time?

When you changed to 134a, how long was the system inop? There is so much to the system that most people do not understand. If the system was blowing hot before and for longer than a week, you must replace the drier. If not there was too much moisture in the system. Also did the tech change the oil to PAG 100? If he didn't, that could be a huge issue. Not draining the old oil, adding too much oil, will all cause the system to perform very poorly.

Personally, I would take it back to the shop, tell them to how you the readings and tell them to either do what they are supposed to do or give you your money back You should be at 35-50 on the low and 260-310 on the high side for our cars, all is still dependent on the outside temp. If the system calls for, say 24oz, you need 15% less if converting from r12. I know this is a lot to take in, but there is a lot to a climate control system.

If the line is cold, it should be freezing feeling, not just cold. HOw does the other line feel? It should be actually quite hot. If it is not, you have a block in the system. The pressures will show that, I think the shop is full of crap if they say the pressures are good.

[emiliog2276]

I might be of no help since my is still running the original R12 system. Had warm are for the longest until i narrowed it down to the suction throttle valve as soon as that was replaced cool air like it was a winter wonderland.

http://z32.wikispaces.com/suction+throttle+valve

[t.mcginley.jr]

When you convert to r134a you have to change the expansion valve to get cold air (at least in our cars, can't speak to other makes/models).

I've done this exact same thing... the system was already empty of r12, so I pulled the compressor and changed the oil to the correct PGA oil for r134a, changed the hi/low side fittings, and installed a new receiver drier/accumulator, filled it up with almost 2 cans of r134a (using manifold gauges of course) and still nothing but mildly cool/slightly less hot air. I couldn't add any more without making pressures too high, so obviously it's the expansion valve causing the problem. In hindsight, I should have changed out the expansion valve while I had my dash out for the heater core job.

The expansion valve is only like $15 on RockAuto, but getting to it is a PITA.

[nissanfreak12]

When you convert to r134a you have to change the expansion valve to get cold air (at least in our cars, can't speak to other makes/models).

I've done this exact same thing... the system was already empty of r12, so I pulled the compressor and changed the oil to the correct PGA oil for r134a, changed the hi/low side fittings, and installed a new receiver drier/accumulator, filled it up with almost 2 cans of r134a (using manifold gauges of course) and still nothing but mildly cool/slightly less hot air. I couldn't add any more without making pressures too high, so obviously it's the expansion valve causing the problem. In hindsight, I should have changed out the expansion valve while I had my dash out for the heater core job.

The expansion valve is only like $15 on RockAuto, but getting to it is a PITA.

This isn't always true, I have changed out a few z's to 134a without doing the expansion valve. If the valve needs to be changed out, its because the valve is not functioning properly or plugged with debris, which in this case could be the culprit.

[t.mcginley.jr]

When you convert to r134a you have to change the expansion valve to get cold air (at least in our cars, can't speak to other makes/models).

I've done this exact same thing... the system was already empty of r12, so I pulled the compressor and changed the oil to the correct PGA oil for r134a, changed the hi/low side fittings, and installed a new receiver drier/accumulator, filled it up with almost 2 cans of r134a (using manifold gauges of course) and still nothing but mildly cool/slightly less hot air. I couldn't add any more without making pressures too high, so obviously it's the expansion valve causing the problem. In hindsight, I should have changed out the expansion valve while I had my dash out for the heater core job.

The expansion valve is only like $15 on RockAuto, but getting to it is a PITA.

This isn't always true, I have changed out a few z's to 134a without doing the expansion valve. If the valve needs to be changed out, its because the valve is not functioning properly or plugged with debris, which in this case could be the culprit.

Which is probably why mine didn't end up working

At the time I didn't care about the A/C, just about the heater core... because it was freezing out lol

[nissanfreak12]

Its all good now, at least the AC works.