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Schrader valve cores

wptski on Wed June 19, 2013 3:27 PM User is offline

I have a few different adapters for R12. I also have a h/l conversion adapters. It appears that the way the conversion adapters are made , you need to remove the valve core from the vehicle. I see now that some cheaper aluminum conversion sets are made different and work right on top of the R12 valve core.

Anyway, I just got delivered today, a double ended Mastercool 91290 R12 valve core tool for standard & GM large bore. I have coming their 81290 which they call a universal R12 and R134A tool. The 91280 fits in my high side R12 gauge hose adapter and the high side R12>R134A adapter as well. The low side R12>R134A adapter in out in my garage right now.

Had a 90 deg. R12 high gauge hose adapter with a Schrader valve in it. The small end fit, moves a few turns and meets resistance same as my straight adapter did but a bit more pressure it loosens up, a few more turns gets tight again and comes out but in pieces. Won't go all the way in now. Hope this doesn't happen like this on the vehicle?

On a R12 vehicle, one end fits the high side and the other fits the low side which wasn't tight. On a R134A OEM vehicle, the small end fits the high side.

I got both because I was confused by the descriptions and still am! What's the deal with these valve core sizes? I know if you look at the valve cores themselves, they list different ones for different vehicles and a some high flow versions which have a visible spring around the stem.

Edited: Wed June 19, 2013 at 7:34 PM by wptski

iceman2555 on Wed June 19, 2013 9:36 PM User is offlineView users profile

The 90 degree/right angle adapters require the removal of the OE Schrader valve. Due to the flow characteristics this is mandated. The cheaper aluminum with a valve core depressor should never be used with a retro fit. This adapters were always prone to leakage. This adapter did not require the removal of the OE Schrader valve but used a plastic depressor.
The correct adapters for a retro fit will follow the OE size requirements for a 134a system. There are right angle adapter for both low and high side...simply use the correct one for your particular application.
Always preferred the brass or steel adapters. They actually require the removal of the OE valve. This adapters have Schrader valves built into the adapter.
Keep in mind when servicing a retro fitted system that operational pressures are almost meaningless. The introduction of 134a into a system that was never designed to operate with this refrigerant almost negates the 'charge to a specific pressure and temp'. Start with a 90% variance and work from there. If the system is not flushed and cleaned, then a lesser amount of refrigerant will be necessary to compensate for the extra lubricant. Be sure to utilize the correct viscosity lubricant for your particular compressor. Not a fan of POE/Esters, the viscosity may be a bit high for some compressors. But that is just my $.02 worth.
Changing the condenser to a updated unit will greatly aid in performance for the system.

The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

wptski on Wed June 19, 2013 10:21 PM User is offline

Your way ahead of my plans but thanks for the extra info. It's a R12 vehicle with a leak still has part of the 12oz of R12 installed and I'm waiting on a electronic leak detector. If R12 is all gone by then, I plan on a part of a 12oz can of R134A static charge to detect the leak. Depending how that goes will determine which way I go.

Okay, I see the point on the use of the proper R134A conversion adapters which I have. I have a R12>R134A can tap adapter which is threaded for a valve core which I want to add.

What's with all these different types of Schrader valve cores? It's crazy!

How tight should these valve cores be installed? As I mentioned, one was barely finger tight.

Edited: Wed June 19, 2013 at 10:36 PM by wptski

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