Automotive Air Conditioning Information Forum (Archives)

FarSide792 on Sun October 13, 2013 11:22 AM

Year: 1998
Make: Toyota
Model: Tacoma
Engine Size: 3.4L
Refrigerant Type: R134a
Ambient Temp: 80
Pressure Low: 43
Pressure High: 215

My original compressor of 15 years was on its last leg (all the deep water adventures didn't play well with the bearing on the clutch pulley). I bought a new compressor/clutch, dryer, expansion valve from Adv (OE stuff) and replaced the components with very little issue. I purged the evap, condenser and lines with some A/C cleaning stuff in a can ($12 adv auto purchase) then blew them all out with compressed air until they were clear and dry. Added back ~7.5oz of PAG46 between the compressor (I drained the oil that shipped with the compressor), evap and dryer. Buttoned everything back up and pulled a vacuum for ~30 min, then shut it off and let it sit for another 30 min...no loss of vacuum. The truck calls for 21oz of r134, so I ended up putting in almost 2 12oz cans (lost a little burping the lines and left a bit in the last can).

It definitely holds the refrigerant and has a low/high pressure at idle of 43/215.

The sight glass runs perfectly clear for maybe 20 seconds when the compressor is turned on, but then it becomes cloudy (guessing due to a bunch of little bubbles) and it remains this way while the compressor runs (not sure if this is good/bad). The real issue is that the air coming out of the vents is just cool...not nearly cold. I'd guess maybe 65 degrees (don't have a thermometer handy, but its definitely not cold like it is suppose to be). Any ideas as to why its not cold? I spoke with a guy at Adv Auto and he mentioned that the condenser might be clogged in one of the veins?

Things seem fine otherwise...the low pressure tube going to the evap is fairly cold and the high pressure tube is rather hot (again, not sure if this is normal operation). Any suggestions would be greatly appreciated!!!

mk378 on Sun October 13, 2013 10:12 PM

Get pressures at 1500 rpm. If the high side is going way up (it's already too high), the fan clutch may be tired and the condenser overheating. Also any time the $12.00 flush is used, you have to think solvent contamination. With a simple bad clutch bearing it's better to just replace the compressor and drier and leave the rest alone.

I think it has an old-style TXV with a separate sensor bulb. Installing those improperly leads to poor performance. The sensor needs to be correctly positioned and insulated from external heat. If you set the interior fan on low, the low side should drop and the air get colder-- if not the TXV could be a problem.

Edited: Sun October 13, 2013 at 10:13 PM by mk378

FarSide792 on Thu October 17, 2013 7:45 AM

Thanks for the reply mk378!

I checked the pressures again (5 days after the install) and they were still the same....so at least there is no leak in the system. When taking pressures at ~1500RPM the low side definitely drops down to ~34 and the high goes up a bit (not much) to maybe ~230.

The expansion valve didn't have a sensor bulb, but more of a pigtail type thing. The factory one was maybe a .5" longer than the one on the replacement valve (the pigtail*).

Also, if i set the air to low I really don't notice that much of a temp difference from the high setting. With all this being said though, the air has definitely gotten colder over the past few days. Perhaps there was some moisture in the system? It's not ice cold all the time, but it is definitely acceptable most of the time.

Cussboy on Thu October 17, 2013 2:50 PM

Quote
Originally posted by: FarSide792
I checked the pressures again (5 days after the install) and they were still the same....so at least there is no leak in the system. When taking pressures at ~1500RPM the low side definitely drops down to ~34 and the high goes up a bit (not much) to maybe ~230.

Don't go by my thoughts, because I am NOT a licensed refrigeration tech, wait for the smarter guys to respond. But I think that your system is a few ounces low on refrigerant. There are many systems that run in the upper 200s for pressure on high side at 1500 rpm. Low pressure reading seems fine.

Also, you used cans to fill, and one cannot get the full stated amount into the system. If it was mine, I'd add half a can of R134a and try...

FarSide792 on Thu October 17, 2013 3:33 PM

Quote
Originally posted by: Cussboy


Don't go by my thoughts, because I am NOT a licensed refrigeration tech, wait for the smarter guys to respond. But I think that your system is a few ounces low on refrigerant. There are many systems that run in the upper 200s for pressure on high side at 1500 rpm. Low pressure reading seems fine.



Also, you used cans to fill, and one cannot get the full stated amount into the system. If it was mine, I'd add half a can of R134a and try...

So...I did end up trying to add more refrigerant and the low side pressure went up to maybe 47/48 and the high went up to almost 300...which I then deemed to be a bit on the high side. It still produced the same basic results for temp (not being ICE cold...just cool). It seems to vary as it is now...sometimes rather cold..and then others not so much. Odd.

Jag987 on Thu October 17, 2013 10:42 PM

Besides the bearing going out, how was the system working before the compressor was changed? I too am wondering about air flow over the condenser. If the compressor was getting weak, low high pressure, maybe there is not enough airflow/cooling across the condenser to remove the energy (heat) of the now higher pressure refrigerant. Lightly spray a little water ofer the condenser with a hose and see what the pressures and vent temp does.

-------------------------
I bought a can of 134a at w**-mart that had a stop leak, oil, and dye in it. It also had a hose and a gauge, so now I'm an AC pro!

Cussboy on Fri October 18, 2013 2:19 PM

Yeah, poor airflow like a worn fan clutch will cause AC pressures to run high. Here in Arizona, I've replaced the fan clutch on my B2200 and Frontier trucks about every 6 years.

I'm assuming that this Tacoma has a fan and fan clutch and not electric fan. If electric fan(s), be sure all engine cooling fans are on when the AC is switched on.

FarSide792 on Mon October 21, 2013 8:54 PM

The system was *eh* at best before. I mean...if you went on a hour or so drive, you'd eventually turn it down from high to med/low speed, but it hasn't been an icebox in years. The condenser is covered by the main radiator fan, which is always running (and very well I might add). I haven't tried spraying the condenser with water yet, but I will when I get a chance. It really seems that the A/C is working rather well when the temp is just a few degrees cooler out (high in the upper 70s as opposed to the mid 80s). I almost want to say that there is still too much r134a in there?