Holio

I've just completed a 134a conversion on an 84 Z28 with a single electric cooling fan. I'm getting very high pressure on the high side (300psi). I'm pretty sure my stock condenser is not cooling well enough. I believe I have two choices, either get a new Parallel Flow Condenser or go to a dual fan setup. What does everybody think. My engine cools well enough, so the only reason to go to a dual fan would be for better cooling of the condenser.
Thanks

Danno

How much 134 did you put in? You put in less 134 vs. 12 refrigerant. Did you check the rad area for leaves and crap. A second fan may help but should not be required if everything was done correctly. What exactly was replaced in the system when you converted?

Holio

I replaced the compressor, accumulator and blue orifice tube. Flushed evaportor, condenser and all the lines. Filled with 6 oz. of Ester oil and then had it evacuated at a shop. Brought it home and charged with about 28oz of 134a and 3oz of performance enhancer. I charged at 1500 rpm (hi side: 300 psi, low side: 30. Pressures at idle are: Hi side: 250, Lo side: 40.
The best vent temp I'm getting on the road is 50* (90* ambient), I figured it should be better.
Thanks Danno

Holio

Sorry, forget to mention, I did a very good cleaning of the condenser and radiator and surrounding area.

jeffs82z28

What do you want to do ? Store beef in your car?

50* outlet temp at 90* ambient, isn't bad at all.

Maybe you have a blower / ducting issue, that is if you don't seem to have the cooling effect that you are looking for.

R-134a operates at higher pressures, and yours don't look too out of wack, maybe a touch high at idle.

how high is the high side pressure when the fan turns on?

Danno

What flushing agent did you use. If it was R-11 you may have major problems. ANY residual R-11 will react with the new oil possibly causing compressor problems. GM recommends for a retrofit that the system be evacuated but not flushed. They recommend no flushing agent at this time. Thier recommendation is the use of an inline filter. What has me curious is that my reference says 84 camaro systems took 48oz after total evacuation. Using the conversion formula that would mean 38oz of 134. Assuming you have the correct amount the only thing coming to mind would be moisture in the system which the dessicant will remove. Try checking it in a couple of days. I went through this with my 89, deciding what to do. I paid the price for 12 and compared to my wife's and daughters cars both 99 GM's I am glad I did. Mine puts ice on my nose.

Holio

Thanks for the replies guys. I used the a flushing agent from AC Source, sorry got rid of the cans already but I know it didn't say R11 on it anywhere. Yea Danno, total R12 charge would be 48 oz for my car. Converted to 134a is about 38oz, does the 38 include the oil, that means I'd be about right than with 28oz 134a, 3oz performance booster and 6oz oil puts it at 37 total.
Also, my fan is always on when the AC is on. I stated above that the lowest vent temp I got is 50*, it does go up to 55* or 60* around town and in stop and go freeway traffic. We get plenty of that in So.Cal. Anyhoo, 55* to 60* vent temps end up to be just barely cool thoughout the car. The wife don't like it, and because she don't like it, I don't like it, if you know what I mean.

Thanks again, Gary

88Bravo

50* is a little high. R-12 you could see around 31-33*. I used rubbing alchol to clean my system. Your fan should come on once you turn on the AC. Is the blower fan kicking on enough? Do you have any leaks on your vents or lines? You didn't have to replace the compressure unless it was bad. The accumulator is the silver thing that the bottles hook up to correct? I did the same thing to mine and was getting about 38* out of the vents. The only problem is that when my car got hit a week before it put a hole in my condencer!! I too only have one fan.

Danno

We did an 81 vette yesterday. Outlet temp 41-45 degrees with 134. Like many here I have self educated myself with some good textbooks since I was considering a retrofit. I am not an expert, but here goes anyway. Looking at two reference manuals they do not specify the oil/ref as an additive. They say 6oz oil, 42oz ref. So in theory, you are a little low. First thing I would do is look at clutch cycling. Do you have a CCOT type or the newer Harrison V5 compressor. They changed over in 85 according to my manual. If your pressure is that high the high pressure switch may be limiting comp clutch operation. I think the high press switch kicks in at about 255psi or so. If it is a CCOT normal clutch cycling is roughly 8x/min. If it cycles more than that a clogged orifice tube may be at fault. If it is less feel the accumulator input and output tubes. If the inlet is warmer or both about the same it means ref is low. If the inlet is colder than the outlet same thing. If the correct amt of ref is in the system the orifice is suspect. Hope this was of some help. To the guy who used rubbing alcohol bear in mind it contains water. You can purchase anhydrous alcohol at many paint stores. It contains no water and works well for a lot of different things. You mentioned it was a new compressor. GM points out in servicing instructions about fine metal pieces possibly plugging the orifice which is why they suggest an inline filter. Hope that ain't it.

Holio

Yes Danno, I believe you are right, I am undercharged, that's pretty much what I've suspected. I have a new/reman. R4 compressor, it has a High Pressure Cut-off Switch on it. It's only function is to cut-off compressor operation at pressures above 325psi. I have the CCOT type system, and the low pressure cycling switch does cycle the compressor about 8x/min., maybe a little less. I also went with a slightly smaller orifice tube on the recommendation that it would work better with the smaller molecular size of 134a (maybe it is plugged).
I believe my goal is to get more refrigerant in the system, but I don't want to unless I can get my pressures down by either cooling the condenser or going to a better one designed for 134. I may have a slightly plugged condenser anyway, or I may have a little air in the system, I thought I was careful about that.
I'll do a little more troubleshooting.
Thanks Danno, good info