A/C system performance temps, new compressor

[Salonika]

Just got my system charged up today after replacing my compressor. I was measuring the temp at one of the vents with an IR gun, and I was measuring temps in the mid 20's a few times. Is this normal? Should it be that cold? I know it sounds like a funny question but I don't think I've ever seen temps that cold from car a/c systems..........is there a risk of the evaporator freezing up on me? Could there be something wrong?

 

[DirtyDC05]

I just charged mine today, I evac the system and it pulled out like .78 oz of r 132. Per the sticky on this forum I added 27oz or 1.6 lbs of r-132 . It doesn't seem much colder than before. The thermo reads about 45 deg , outside temp was around 95. Not sure what is normal .

 

[Eljefe]

IR thermometers are very inaccurate to measure air temperature, try using a probe thermometer and you'll see a big difference. At 20 degrees the evaporator will be definitely be iced up.

 

[brad2274]

I just emptied my system and changed the dryer/receiver and got it recharged, much colder now, ill try to measure mine today but im guessing no colder than like 35-40. And what others said, try a real thermometer for air temp.

I just charged mine today, I evac the system and it pulled out like .78 oz of r 132. Per the sticky on this forum I added 27oz or 1.6 lbs of r-132 . It doesn't seem much colder than before. The thermo reads about 45 deg , outside temp was around 95. Not sure what is normal .

Did you change your receiver/dryer while you had it empty?

 

[bikerjosh]

Same experience here. Charged my system at home shut down bottle at 50psi in system, temp probe in vents yielding about 42F w/outside temp being mid-hi 80s.

 

[DirtyDC05]

Did not replace any parts , just evac the system , vacuumed the system . Added same amount of pag oil I removed and charged the system.

 

[Salonika]

Just checked again with a stick thermometer instead of IR, measured about 49 degrees in center vent. I wish I would have used the stick at first, because I swear this thing was blowing colder than 49...........unless I'm losing refrigerant, pretty sure I am not.
Maybe with a fresh charge it takes some time to properly distribute throughout the system. I'll keep an eye on it to see that it holds now at 49'ish. My IR measurements were done at 70 degrees ambient, today it was 80 outside.

 

[RyanY]

Outside temps will have a direct influence on your vent temps - if the outside temps are hotter then you can expect the vent temps to be warmer as well.

 

[Eljefe]

One thing I did to improve the A/C performance was to increase the compressor cycle time by installing a 36K ohm resistor across the terminals of the evaporator temperature thermistor, also installed dynamat extreme on the floor from the footwell all the way to the rear seats. I live in Phoenix and the center vent temps range between 44-48 F at 110F outdoor temp. Also make sure your condenser coil and radiator are clean.

 

[Offroadmuch]

Outside temps will have a direct influence on your vent temps - if the outside temps are hotter then you can expect the vent temps to be warmer as well.

This is only true if you run your A/C on the non-recirculated air setting (button with an arrow going in a circle.) On an American car it is sometimes referred to as Max (recirc.) air setting. If you recirculate it is much easier to keep air cold overall. Recirculated air is good for on trails because you are not sucking in dirt to your cabin and on the road you are not sucking in air from diesels or other smelly exhaust.

 

[brad2274]

This is only true if you run your A/C on the non-recirculated air setting (button with an arrow going in a circle.) On an American car it is sometimes referred to as Max (recirc.) air setting. If you recirculate it is much easier to keep air cold overall. Recirculated air is good for on trails because you are not sucking in dirt to your cabin and on the road you are not sucking in air from diesels or other smelly exhaust.

this is true about recirc but outside temps still come into play. in several 90s cars youll get colder recirc AC at night than recirc during the day. with me being in florida, this is likely due to dash heat-soak. Even while running on the highway for an hour with AC on full blast cold, your dash can be hot to the touch from sun.
This translates into warmer VENT temps, due to non insulated plastic vent tubes, your AC is still working them same but air is passing through warmer vents when its hot and sunny out.
You also (now this is where window tint can help alot with more than just parked cars) will have your interior being constantly cooked by the sun, increasing surface temps inside. That translates to the air not being as cold before it gets sucked back up through recirc.
your AC is naturally going to have a harder time cooling your car on hot sunny day vs cloudy/dark.

 

[quailchaser]

Ditto cleaning the condenser and radiator. I removed mine and cleaned it with degreaser and boiling water, then vacuumed it and recharged. Same operating pressure, but much cooler. Did this on another car as well. With 200,000 miles, I guess a lot of greasy film builds up on the condenser over time.

I'll have to try the dynomat trick. I tinted windows, but AC still struggles when it is over 100 degrees up here in NW AZ. I'm just glad our 112 was cooler than Phoenix's 118 the other week.

 

[RyanY]

Outside temps will also affect how well your condenser functions - higher ambient temps mean that the ability of the condenser to radiate heat will be reduced, which will reduce the overall a/c system performance.