Quzyle

iTrader: (1)

Hello, I need some help, and don’t know where else to turn. Was hoping that someone on here could help. I have an 89 Suburban that has 2 zones of AC, front and rear. When I first got it years ago, the old R4 compressor had failed. I installed a new compressor and was going try and learn how to recharge the system. But instead I took it to the dealer and they went through the entire system and flushed everything, installed new o-rings, orifice tube, expansion valve and charged the system. The system was great other than the crappy R4 noise. Fast forward a few years and I have installed a gen 6 big block with the sanden compressor. I took it to a local shop that was highly recommended. They built a set of hoses to match the old with the new, charged the system. This is where thing to a turn for the worst. There welds leaked. I had to take it back several times. Finally they seemed to fix the leaks and then the compressor started leaking. I am out of town a lot, so projects take me forever, I decided that I wanted to finally figure this stuff out. So I installed a new compressor and dryer. I vacuumed the system down, check for leaks, all seemed good. I started adding R134. It was slow to take it in, but eventually it had about 60oz with about 8 oz. of oil. It never seemed to be that cool. A few weeks ago I started the Suburban up to move it and notice that the AC was not working. It doesn’t get driven much, 200 miles a year or so.
Today I check the pressure and it had about 10 psi in it.

So I thought that I would add a little more to the system, thinking that I just did not get it filled last year. I added 36 oz.. Again it was slow to take it. And that took the low side to 45 to 50 psi and the high side to 325psi. It was 99 to 101 at the time and at an idle. The vent temps where between 70 and 80, but there was no rear cooling and the dryer was very hot.. If I raised the rpm, the vent temp dropped to about 65-70 and the pressures dropped as well, but I am not sure what they were. So here is my questions: What am I doing wrong? How do you know you have enough Freon in? Do I just keep adding Freon? When is it not safe to add any more?

I want to learn and figure this stuff out, but if I need to take it to a pro I will. Any good recommendations in Wasatch Front area?

Sorry for the long post, and thanks ahead of time.

92RS-HeritageEd

iTrader: (2)

While I am NOOOOO expert, I just did the A/C on my 97 Dodge Dakota...

What am I doing wrong? Was the clutch cycling? The psi's you provided were they with the engine on, and AC clutch engaged or was that the static pressure?

How do you know you have enough Freon in? When your manifold gauge set reads the correct low side & high side pressures as implied on the r134a reference chart.

Do I just keep adding Freon? Absolutely NOT

When is it not safe to add any more? When your manifold gauge set reads the correct low side & high side pressures as implied on the r134a reference chart.

I want to learn and figure this stuff out, but if I need to take it to a pro I will. Any good recommendations in Wasatch Front area? Youtube - Ratchets and Wrenches Chanel

Quzyle

iTrader: (1)

Thanks for the reply.
The psi provided was with the engine on and at an idle. The clutch was not cycling due to low pressure. I jumpered the low pressure switch and added 12 oz. of freon. After that I removed the jumper(the compressor stopped) and plugged it back in the compressor restarted and continued to run until I shut off the AC system.

It looks like I am at the correct gauge pressures or at least very close. It is 100 deg outside. The low side was at about 45 and the high side was at 325.

Could this be a problem with not enough air a crossed the condenser? I don't remember what fan I used, the 89 5.7 or the 99 7.4 unit.

Thanks again.

92RS-HeritageEd

iTrader: (2)

Please understand, I am not an ASE Certified mechanic, far from it. Based solely on the information your providing you may actually be low on refrigerant. 12oz seems a little low... my system takes 28oz total r134a and 240cc of PAG 100 Oil. What I've learned (within the last 24hrs) is that the psi's are only accurate if your clutch is engaged.

EXAMPLE: I added about 8oz or so using the DIY recharge kit, and without the clutch engaged the psi led me to believe I was over psi on the low side, and low on psi's on the high side. However, once I consistently applied 12v directly to the compressor clutch it remained engaged and ONLY then did I get an accurate reading on my Manifold Gauge Set, lowside was around 10psi and high side was around 125psi. I then added another 12oz can and it rose lowside to 35psi and the highside to 175psi. I now have crisp air...

1. What does the sticker say the capacity is for both r134a/r12 and its respective PAG Oil?

I'm just sharing my experience as a noob, I was hoping one of the supreme members or moderators chimed in LOL! I've also posted a few vids that helped me.

Quzyle

iTrader: (1)

Thanks for your desire and wiliness to help. That is what makes this place great.

I have a fairly good grasp on the basics and book knowledge. I am lacking in the practical experience.

The system was converted to 134 years ago, but the sticker is no longer readable.

I like watching the RnW videos. He does a nice job.