AC Manifold Gauge Set

[fixt]

I need recommendations for a quality gauge set.
I don't want a cheap set and don't want to break the bank either.
The tool will see intermittent use.

Is brass or aluminum manifolds preferred; why is that?
Some quick couplers have a valve on top. Is that to depress the shrader valve?
I see those with Ritchie Yellow Jacket and Mastercool.
I don't see the need for a 4 valve set or even a sight glass.

I'm looking at Mastercool and Robinair mainly, including the Mastercool digital gauge sets. Ritchie stuff is nice but expensive and beyond my needs. I'm open to other makers if someone could make a recommendation.

My AC blows cool but not cold. All functions work correctly. I have no idea when the AC was last serviced and I suspect it may be a little low. I'm at the point where I need pressure readings before proceeding.

 

[scdix50]

I have used the set from Harbor Freight many times over.

 

[BrooklynBay]

I have two sets from Interdynamics for many years.

 

[fixt]

Thanks for the replies.
I looked at the Interdynamics, but had never heard of them.
I tend to avoid Harbor Freight if possible

I guess there's no real advantage of brass over aluminum?
Longevity maybe or any corrosion issues?
What about the couplers with the valves?

One advantage of the Mastercool set: it had everything in it to include a can tap and long stem thermometer along with the quick couplers.

 

[willisan]

I have used the set from Harbor Freight many times over.

The HF one is for 134. I have a 93, so an r12 system. Can I use a 134 gauge set as long as I have r12 to r134 adapters on the ports, or is there something else different with the gauge set?

 

[BrooklynBay]

The R134A gauge set is only used with R134A freon. If you convert your R12 system to use R134A, then you have to use R134A guages.

 

[willisan]

Thanks BB

The r-12 system is currently empty (though still oil in it), and I was going to repair it and use an r-12 substitute so I don't have to buy a new compressor.

The hose from the comp -> condenser broke, so I figure I would replace that, the dryer and perhaps orifice tube.

I have been reading the conversion threads, but I was hoping to get by without swapping compressors, so I figured I would try r-12 substitute and keep the current setup.

 

[BrooklynBay]

R134A could be used in an R12 system without swapping the compressor just as long as there is no R12 in the system. Never mix refrigerants.

 

[fixt]

Thanks for the replies.
I looked at the Interdynamics, but had never heard of them.
I tend to avoid Harbor Freight if possible

I guess there's no real advantage of brass over aluminum?
Longevity maybe or any corrosion issues?
What about the couplers with the valves?

One advantage of the Mastercool set: it had everything in it to include a can tap and long stem thermometer along with the quick couplers.

Since this got bumped, I'll update.
I got the mastercool set; there is no thermometer included. The quick couplers for R134A work fine. R12 hoses are included with the set I got from Amazonia. I got a candy thermometer and checked calibration in an ice bath which should show 32.43 F, if you can read it that close.

The main thing is refrigerant cross contamination and oil miscibility, the refrigerants need different oils to carry through the system in the refrigerant.
That and it's not so clear cut as to how much R134A refrigerant to use when doing the conversion. There's some rules of thumb but fine tuning the system may require some fairly specialized tools for the exact charge along with the new R134A adapters and system tags.

 

[ranger7ltr]

This should not be an issue...

Since this got bumped, I'll update.
I got the mastercool set; there is no thermometer included. The quick couplers for R134A work fine. R12 hoses are included with the set I got from Amazonia. I got a candy thermometer and checked calibration in an ice bath which should show 32.43 F, if you can read it that close.

The main thing is refrigerant cross contamination and oil miscibility, the refrigerants need different oils to carry through the system in the refrigerant.
That and it's not so clear cut as to how much R134A refrigerant to use when doing the conversion. There's some rules of thumb but fine tuning the system may require some fairly specialized tools for the exact charge along with the new R134A adapters and system tags.

Because if you are converting an R-12 system to R134a you should be pulling a strong vacuum on it in the first place...There will be no cross contamination of the refrigerants...And if you converting then you need to do a thorough flush to remove the mineral oil that R-12 uses and add your oil of choice for R-134a...

Generally R134a runs at a higher pressure than R12 and in a coversion you want to start at ~70% of R12 charge level and adjust from there...Also R134a is more sensitive to cooling system issues and demands more attention to the radiator, coolant, thermostat, and cooling condition than R-12 does...The biggest problem I have seen is someone overcharging R134a into the R12 system...

You really need to monitor the high side pressures and the vent temps to keep the system healthy...

Also there is little if any oil in the compressor...The majority of refrigerant oil is in the accumulator and the condensor...And any mineral oil that would happen to be in the system will collect in the lowest point of the component it is in because R-134a will be adequately move mineral oil ...