Ok, need to see what everyone has experienced with their R406a conversions. I don't remember what I saw back in 2007 when I did this previously but it seems I am not getting as low vent temperatures as before. Everything is new in the system, new Evaporator, new Condenser, new Accumulator, new Orifice Tube, new Clutch Cycling Switch, and Reman Compressor... Charged with 3 cans of R406a..

My static pressure with engine off and at 55F ambient is about 64psi. Clutch cycles between 25psi and 42psi low side pressure with a corresponding 100 to 130psi high side pressure. Once in a while the high side pressure will get as high as 240psi (low side hasn't dropped to cutoff the compressor yet so it is still running) and then the fan kicks on dropping the high side pressure back down to 125psi or so. Then, it goes back to normal cycling for a while and occassionally repeats the high side pressure climb until the fan kicks on....

Is this about what everyone else has seen on their systems with R406a? I am wondering if I am a bit low on the freon even though the 3 cans is exactly right for a 92 3.1L. Thinking that maybe the new condenser is slightly higher in capacity. Thoughts? Experiences?

Thanks...

 

What state are you in and what are your weather temps?

120 psi is extremely low (on the high side). Most of the time it will hover between 190-250 psi. Once that secondary fan turns off, the high side should hold that pressure and start to rise back up.

I trust you had the system vacuumed when you changed out everything?

What kind of orifice tube (color) did you put in?

How often is it cycling while idling in your driveway? With summer weather here in Houston, it really doesn't cycle much if at all when idling.

Should be running around 35-40 psi and 200-250 psi just while idling and running the A/C.

 

Yup, I have regular vacuum pump for doing A/C work so pulled a vacuum for about and hour.. I am in Washington state and the ambient was around 55 to 60F when I took the last readings.. Cycle on time is about 20 to 40 seconds (guess) and off about 3 to 4 seconds.. The orifice tube was supposed to be stock and came already mounted in the evaporator.. Appeared to be white.. The evaporator said R12 and R134a compatible.. I wonder if they fudged the orifice tube because of R134a.. I just put about 100 miles on it with the A/C running but didn't see much difference (improvement) in lower duct temps. I don't have my gauges with me on this trip so can't see if the cycle pressures have changed now that I have "broken in" the new components.

When I get home tomorrow I will run a vent temp check. When I had it charged before, I was getting 32F at the vent. Not sure what you mean by secondary fan. This is a stock single fan system. By the way, the radiator is also new along with the water pump so the engine cooling system is in very good shape.

 

I thought you had the dual fan setup. So disregard that.

Your system may actually be running just fine if the temps outside are 55-60. I've found that the "feel" temps don't seem as extreme when the weather is mild temp/dry outside compared to the peak of summer. It's simply a factor of it's 60 outside and blowing 30 inside vs it's 100 outside and blowing 30 inside. I have a friend in Vegas who says that when he walks into a mall in the summertime and it's 115 outside and then drops to 70 the second you walk inside the mall doors that it's like walking into a deep freezer. I notice the same thing at work here in Houston. When I walk in the doors first thing in the morning during summertime, it's quite frigid for the first 30 seconds. But walking inside during the spring/fall, it doesn't feel much colder. But rather just drier. (I work in a Hospital with strict temp/humidity settings)

The other factor is that at 55-60F outside, the system will cycle off too often to get the super low temps. To get down to 32, you really need the system to run for long periods of time.

120 psi probably is achievable on the high side if there isn't much in the way of heat to reject from the system. This would be the case in 55-60 weather. Although I've never actually measured the system pressures at that low of an ambient. It's rarely that cool here except for in December.