Need some help if there are any AC guys on here..

Looking at the front AC line to the passenger side of the AC cond. up front there is a connection there right near the temp reader.. that point always has this hissing sound like its leaking when running; when you turn off the engine you hear the hiss taper off..

Dad thinks its leaking.. and being the AC doesnt always work well he things when pressure is high / temps high he thinks the Orfice tube might have an issue or glogged.

I'm looking on Rock Auto and i see a few i need suggestions on.. I live in humid South/South East Texas.. and I show 3 possible parts..

FOUR SEASONS Part # 38641 Orifice Tube
OE Replacement


FOUR SEASONS Part # 38903 Orifice Tube
Optional Automatic Adjusting Orifice Tube for normal climates (105Degree-)


FOUR SEASONS Part # 38905 Orifice Tube
Optional Automatic Adjusting Orifice Tube for severe climates (105Degree+)



I'm not sure which one to go with.. anyone give me suggestions.. will the OE one work? Or should i be running one of the others?

Secondly the hissing soudn sound like a leak to all you guys? the low side during about upper 80's/low 90's showed about 40* (degrees) on the gauge.. Dad said it was too high.. either needing more refrigerant or there was orifice issue being there sounded like a hissing leak.

 

Your readings are a bit confusing. I think you mean at 80/90 degrees it is showing 40 psi (not degrees) on the low side. That's NORMAL. 32-40 is specs for 80 and 37-45 is specs for 90.

You may hear some noise at the orifice tube. That's where the pressure drop occurs.

What is your high side pressure? You CAN NOT properly diagnose an a/c system without both readings.

 

no the gauge on the can reads in temps. Left being colder and right being warmer until the red zone.. which is really hot like 50 or 60 degrees..

Unless my dad has gone senile..

 

LOL i was just looking at the different gauges.. I think your right.. not sure what he was looking at then.. but i seen the gauge it was at 40 it was probably about High 80's low 90's outside.

 

Don't rely on the gauge on the can. They are usually pretty inaccurate. You really do need a gauge set, and more, to do this work.

From what you're seeing I don't think it is low on charge. Again, without the high side we can't tell if the orifice tube is restricted or if the compressor is working properly.

Check the condenser coils, make sure they are clean. How's the fan? Is it working?

 

RIght now i have my fan clutch on and yeah it works. ac seems to wanna work better at lower rpm at a stop or lower RPM than at highway speeds wehre youd think the ac would cool better Thats why he's thinking it might be clogged...

 

Get a gauge set or you're just throwing parts at it.

 

I've just been reading more into ac systems recently myself and am not really an expert, but maybe I can offer some help.

That hiss is most likely refrigerant moving between the high and low side there. I'm not absolutely positive, but I think that might be where one of the phase changes occurs too.

I'm currently investigating a similar situation with my ac where it works better at low engine speeds than higher ones too. I'm waiting on a gauge set to arrive so that I can vacuum the system down and refill it.

Those can gauges really aren't a good way to do anything with an a/c system. To do things right you need a gauge set that shows both the high and low sides.

 

It may be the orifice tub is dirty but the next question is why is it dirty?

The only way to check it is empty the system and look at it I have never tried the self adjusting ones.

Removing the orifice tub is usually not easy as they tend to get pushed deep into the tube I used a pressure hose to blast it back out.


I just woke up so in an hour I will give you more info...... fuzzy head

 

some reading for ya


http://www.autoacforum.com/messagevi...threadid=13542