Dash ac recharge on class a diesel pusher

rgatijnet1 wrote:

dougrainer wrote:

Ivylog wrote:

crasster wrote:
Really - while you can DIY recharge, it is BEST if you can put the system under a deep vacuum then charge. It's the proper way to get all the air out so there is more pure 134a.

Really, How is air going to get into a system that is still cooling, but not as cold as normal... is still pressurized and has enough freon in the system to work somewhat? Even while working the low pressure side will have 60+ psi in it... how is air going to get in???

Bingo. HOW can air get into a pressurized system? IF the system has been open to the atmosphere, then yes, find the leak, then Vacuum and charge. Vacuum can also let you know if the system has a large leak. Small leaks that happen under pressure, a Vacuum test rarely is accurate. Now, HOW is a novice supposed to know how much 134a to install? Unless you have your gauges connected and do a digital temp at closest outlet to the evaporator, you will have a hard time getting it filled correctly. BTW, SMALL leaks will not cause Oil loss. TOO MUCH 134a is as bad as too little. Too much and the system will not cool correctly just like too little. A TEST for posters. HOW much 134a(lbs) do you think a average Diesel RV motorhome takes? Doug

If the system is still pressurized then who cares how much freon the system holds? All you really need is a thermometer. Placed in the outlet of one of the ducts, add freon slowly until the temperature drops to it's lowest and starts to go back up. As soon as that happens, you stop. You are right, too much is as bad as not enough so you add for the lowest temp reading.
Now this is not scientific and is not how a tech would do it but for a NOVICE, it will work just fine and probably save them a lot of money.

This is true. You watch the temp gauge and when the temp stops at a certain temp, you wait until it raises a degree or 2. Then STOP the fill. BUT, a lot of novices will not do that and will overfill. Doug