E30 + R134 = not impressed

[LJ851]

Lots of marginal/bad info in this thread!

OP: Is your compressor clutch short cycling? Are there bubbles in the sight glass on your drier? Both obvious signs of low charge. Also, are you certain your heater valve is shutting off all the way?

I dont think it is short cycling, what is normal? I dont remember bubbles, i'll check tomorrow. Heater valve was shutting off last time i checked, will double check tomorrow.

[Ryann]

There are varying degrees of short cycling, but on 5 secs of 5 secs is typical of a system that is getting low on charge. Eventually when the charge gets too low internal pressures drop below that required for the pressure switch to energize the comp. clutch.

[LJ851]

OK gentlemen, i have some data. I see no air bubbles in the sight glass. The heater valve shuts all the way off. The compressor doesnt cycle, its on all the time. Come to think of it i am pretty sure its always been that way cause i never remember the load on the engine changing while the A/C is on. I just took a test drive. Its 87 degrees out right now and i set the A/C on recirculate with the fan speed on "3" through the face level vents only. With the car stationary vent temps are 69-70 degrees. Did a loop on the highway and vent temps stabilize at 61-62 degress. Ambient temp in car after 15 min drive with 2/3 on highway was 85 . Im sure it doesnt help that im black/blackleather.

[Ryann]

Do you have access to a gauge manifold set? You may have a compressor performance issue in which case your suction pressure will remain somewhat constant (instead of cycling) and your discharge pressure will be too low. Carefully reach down and feel the lines at the compressor with your system maxed out and the windows up. One should be uncomfortably hot and the other cool.

[LJ851]

I'll try to find some gauges, it may be time to by a set. I just ran the system maxed out and 1 line at the compressor was hot like you describe, the other line was cool, but just barely. Any warmer and it would have been neutral. The interior of the car was not cooling as usual.

[Ryann]

The cool line should get gradually cooler as your cabin temperature drops. Once the cabin is cool the evap. temp. switch inside should cycle the compressor on and off as needed. The amount of time this takes is of course predicated on ambient conditions.

[LJ851]

The cabin temp never drops when the car is stationary. To get any cooling at all the car needs to be going 45mph+ and its not much even then. The aux fan does come on when the a/c is turned on.

[Ryann]

I'd have to see some gauge readings to be sure but it sounds to me like your compressor performance is in the shitter.

[LJ851]

Thanks for help Ryann, i really appreciate it. I will get you some gauge readings as soon as i can, but it may take a couple days.

[scottinAZ]

I'd have to see some gauge readings to be sure but it sounds to me like your compressor performance is in the shitter.

either that, or he is overcharged. With a 134a system you have to run less refrigerant (2/3 r12 iirc).

I have some bubbles in the sight glass on mine, and with just a hair over 2 cans in the system, its balls freezing cold in the AZ summer (outlet temps in the 45 degree range)

[Ryann]

^As a rule you should charge until the sight glass is clear under typical operating conditions, not necessarily a certain percentage. But yes it is true that an overcharge could cause inefficient operation, as could excessive aux. fan speed or a faulty expansion valve/feeler bulb. Gauge pressure reveals all.

[BrooklynMW]

Open the window. Problem solved.

[Simon S]

Jeez - you guys are scaring me regarding how complex this could/can be.

Funny - I went to this one shop and started asking this guy different questions pertaining to what I read here and there.. evacing, weight vs. volume, lubricants, etc.

Guy just gave me a blank stare and said it gets hooked up to a machine - and the machine just takes care of everything..

[Schnitzer318is]

^Well they do have to tell the machine how much refrigerant to put in. Other than that he is right the machine does all the work. Though when first converting to 134a my shop did add a small amount of oil to the system.

[Huff]

either that, or he is overcharged. With a 134a system you have to run less refrigerant (2/3 r12 iirc).

I have some bubbles in the sight glass on mine, and with just a hair over 2 cans in the system, its balls freezing cold in the AZ summer (outlet temps in the 45 degree range)

Yep. Overcharging will reduce the performance and put added wear on your system. You should only use 75% of what the R12 weight was. I'm running 760Kg's of R134 and have frozen my evaporator a few times... It's cold.

Though, your compressor needs to be up to par and aux fan working well also. I'm thinking about a Spal just for sitting at idle in downtown Atlanta traffic..