Fan Clutch or A/C Problem?

[DaleG]

Problem is poor cooling at idle on 90F+ days. The system was recently serviced for the infamous rusted out accumulator. They replaced accumulator, orifice tube, evac'd and recharged. System was working real well til it got real hot, cooling at highway speeds is good with vent temps as low as 38F. But at idle temps rise. The fan clutch appears to be good, it has resistance when hot or cold and stops turning immediately when car is shut off. The pressures taken after the car had been sitting in the heat, max ac, fan at 2, and running for about 15 mins were low= 45 high= 225 on 92F day, vent temps were only in the 60's. Accumulator is cold on both pipes and sweating. Increasing idle speed will bring temps down some. Condenser is clean and when sprayed with water the pressures come down and vent temps do also. When i hooked up guages before starting truck the static pressures were @ 150psi (seems high to me). Engine cooling system appears to be working normally, guage is right in the middle where it always has been.
So is this an air flow problem, overcharge or something else?

Thanks
Dale

 

[TPLYNCH]

Just curious, when sitting at idle with the A/C running, do you see the water dripping out underneath the truck?

 

[DaleG]

Oh yeah, there is plenty of dripping. The accumulator is sweating and the pipes are cold. I was thinking that the low side pressure should be a little lower, so I'm wondering if they possible overcharged the system. The day I took it in it wasn't a real warm day (maybe 70's) and it was morning when the fixed it.

Dale

 

[Glacier991]

Read this earlier and been thinking on it... I come to one of several problems.... 1) poor air circulation at idle; 2) weak compressor unable to generate higher head pressures when needed; 3) possible overcharge; 4)possible obstruction in orifice tube only apparent at idle.
This one is a curious one. I think I'd start with airflow at idle before I jumped into anything else. Wish I was more help.

Happy Exploring

Chris

ps. THANK YOU for the pressures, LOW and HIGH and temps - ambient and vent.. THAT helps a lot !

 

[DaleG]

I would also add that before I had it serviced I had been charging the unit every so often due to the accumulaotr leak. During all that time I never had any problems with cooling at idle, if fact the temps were always a little colder when idling. So I think it would be a strange coincidence that the fan clutch just happen to weaken out at the same time the truck was serviced.

Glacier, What are the chances this thing is overcharged, Isn't 45 lowside a little high for a 92f day and the compressor running continuously?

Thanks for the insight
Dale

 

[Glacier991]

Dale... your last comment makes sense, on the other hand when you spray the condensor (helping remove the superheat) things drop in pressure, making me wonder how effecient your condensor airflow is at idle speeds - that was all. Yes 45 on the low side IS high, and will relate pretty closely with a 55 or so vent temp... 225 is also a little high on the high side although 134a will produce some higher head pressures than R-12 did. An overcharge is a pretty good probability I'd say... Do you have any way to recover the refrigerant to bleed some off?

Happy Exploring..

Chris

 

[DaleG]

Glacier, Thank you for the insight, sorry if the tone of my message seemed harsh, it certainly wasn't intended to be. I am just kinda puzzled (and hot in traffic).
I'm an A/C tech wannabe, I've been messing with mine so much lately it gets kinda interesting and I like to learn.
I'm actually leaving tommorrow to be out town for a week, so when I get back I'm gonna devout some time to this. I'm due for an oil change and t'stat and flush anyway so I'll probably just take a Saturday and do all that maybe change fan clutch also. I may also try bleeding down some presssure to see if the temps come down.
Once again thanks and all your knowledge is helpful and very APPRECIATED.

Dale