A/C issues

Topic: A/C issues (Read 5493 times) previous topic - next topic

Reply #15 – August 21, 2013, 04:37:05 PM

I have replaced the clutch fan with a very large electric. It turns on low with the a/c, and is pulling a good amount of air through the condenser.

Also, it doesn't cool well while cruising at 75mph, so doesn't sound like a fan issue to me.

I'm wondering about the blend door/clogged evap as the vent temp seems far too high for the pressures.

Chris

A/C issues

Reply #16 – August 21, 2013, 05:06:50 PM

However, when you used water to cool the condenser, the vent temp dropped right in, as well as the pressures. You have a hot condenser. Now we figure out why.

A/C issues

Reply #17 – August 21, 2013, 05:08:30 PM

You wouldn't happen to have a TC nose, would you?

A/C issues

Reply #18 – August 21, 2013, 05:09:55 PM

You wouldn't happen to have a TC nose, would you?
Also, what HVAC system do you have, auto or manual?

A/C issues

Reply #19 – August 21, 2013, 05:15:33 PM

No tc nose, manual hvac.
Cooling the condenser dropped the pressures, but not the vent temps significantly. Vent temps at 250/50 were in the mid 50's
Chris

A/C issues

Reply #20 – August 21, 2013, 05:35:04 PM

You have to remember that your vent temp will always be approximately equal to the low side pressure. Hot condenser-high low side pressure-high vent temp. Causality.

A/C issues

Reply #21 – August 21, 2013, 05:40:52 PM

But with the low side at 26psi, the vent temp was 47.2. Doesn't seem to be correct. Hense my wondering about blend door or evap issues.
Chris

A/C issues

Reply #22 – August 21, 2013, 11:03:52 PM

Clearly you figured out by now you either have a TUBE that is to small or a condenser as well. Along with not enough air across it. When you got the 30 On the low you got cold air discharge from the vents. So the tube may be to small and or the condenser as well. 50 on the low is NO DAM GOOD. With that pressure you are way to HIGH for proper cooling. Better check that TUBE and hose assembly for application. Sounds like the tube is to small. You need around .060-.070 Tube to work correctly. I knoe it is built in to the hose but clearly you are not FLASHING OFF IN THE EVAPORATOR. Your charge is still to high. You need to dump and if by dumping your numbers come down and cooling does not improve you need a bigger tube or condenser!!

A/C issues

Reply #23 – August 21, 2013, 11:08:16 PM

Ok, fair enough. How much do i need to dump? As in try to drop the low side down to 30-35 at 85 degrees?
Thanks,
Chris

A/C issues

Reply #24 – August 22, 2013, 05:58:57 AM

YES YES YES. I am not saying that will work because i am not there in person. But whenever a system is close to 48-50 LBS in 85-90* you are dead in the water. Just look at the charts. And i know it is normal some times to have over 200. But once you approach over 200 You are at the max point. Normal readings at or around 1200 RPM should be 30-35 On the LOW and 200-230 On the high in 95* Just saying. Other wise you wont cool down> GOOD LUCK.

A/C issues

Reply #25 – August 22, 2013, 06:04:10 AM

Check the gauge reading compared to evaporator DISCHARGE CHART. Just run down the number where you low side is and it tells you YOUR DISCHARGE TEMP. @50 You are blowing 54* and that SUCKS. You need APP 40* at the center vent to cool a car in 100* weather Good luck

http://www.csgnetwork.com/r134apresstempconv.html

A/C issues

Reply #26 – August 22, 2013, 11:25:16 PM

Well, it was 70 and raining all day today. Next time its warm and sunny i'll "recover" some of the freon and see what the vent temps do.
Thanks,
Chris

A/C issues

Reply #27 – August 23, 2013, 11:26:12 PM

Ok, it was 88 and sunny today, so I lowered the system pressure some. Was at around 35 low at idle, but when i revved it, it dropped to 28, so i may have removed too much. Vent temps were in the mid 40's, so that was much better. I'm done with it till i drive it somewhere on a warm day and see how it preforms.

What should i set the low cycling switch at? I believe i've read 22psi for r134a.
Thanks,
Chris

A/C issues

Reply #28 – August 24, 2013, 10:24:00 PM

Lower the switch to around 24-26 LBS. When you got the 35 on the low side you are golden. Revving will always send the low side down a bit. This is normal and i bet you AC is working much better. You are GUILTY OF ONE OF THE BIGGEST MISTAKES AMATEURS MAKE WITH AC SYSTEMS. YOU OVER CHARGED IT. Run it for a while and i think you are OK NOW. Good Job!!

NOTE you were flooding the evaporator with to high a charge. Your gauges told you that!!!

A/C issues

Reply #29 – September 22, 2013, 10:08:39 AM

Here is a simple technique to get the most out of a 134A conversion. I followed this method on several r12 cars. The newer vehicles are computer controlled so it won't work. The old Ford system used r12 and a cycle on off switch depending on the low side pressure.

Here's the technique it's real simple. First I assume everything is in good working order. System has been flushed, proper oil, good compressor, evaporator and condenser and orifice tube and acspoogeulator. Forget about the cycle switch all you need to do is bypass so that the compressor is either on or off. Throw that switch away. You'll need a good digital thermometer. Put that in your air vent. Measure the temperature as you add Freon.

Proceed slowly all the time watching the temperature coming out of the air vent. When you get to the lowest temperature it will start to rise. Stop filling the system at this point. You may only need a can or two of Freon.

If you've ever watched the frost on the lines you'll notice that it will move. By that I mean the line may be frozen but as you add more Freon it will melt and start to sweat. What you want to do is find this sweat point (move it) so that it falls on the evaporator core. When it does you're getting the coldest temperature possible out of your vent. Also you evaporator core will not freeze up. There is no need to cycle. Furthermore your pressures are lower, putting less strain on the compressor.

Using this technique I get about a 20 – 25° difference between ambient and inside vent temperature. Needless to say the air works better than new. You’re basically operating on perhaps a third to half capacity but there is no need to cycle, your compressor is on all the time but with reduced pressure and less strain and your evaporator core will not freeze.