A/C No longer Cold

[gixxer600]

Last year it was fine. This year it's blowing hot. The filters in the cab and behind the cab were COMPLETELY clogged ... replaced them, no difference. The temperature knob is very loose feeling ... not sure if it could be bad. My neighbor works at a body shop and looked at it and says we should check the freon. He said we need to know the optimal low and high pressure and operating capacity (amount of freon). Does anyone know this, or have any tips? Thanks! Craig

 

[OldMachinist]

Can't answer your question without knowing make and model of your machine.

 

[Fishfiles]

The way I do it is , start filling and watch the high side and don't let it get pass 250 , the low side should be around 35 to 40 , I mostly fill them with a large can so how many lbs it takes I can't tell you , but from filling them in the past 3 - 12 ounze cans would be in the ball park

 

[gixxer600]

The way I do it is , start filling and watch the high side and don't let it get pass 250 , the low side should be around 35 to 40 , I mostly fill them with a large can so how many lbs it takes I can't tell you , but from filling them in the past 3 - 12 ounze cans would be in the ball park

It is an 07 T300 Thanks Fishfiles. I will tell him that and hopefully that will help. One more question ... how can you run the machine while you fill it? Can you raise the cab with it running? Also, the temperature switch (hot/cold) is very loose feeling. I wonder if it could have to do with anything?

 

[Tazza]

It is an 07 T300 Thanks Fishfiles. I will tell him that and hopefully that will help. One more question ... how can you run the machine while you fill it? Can you raise the cab with it running? Also, the temperature switch (hot/cold) is very loose feeling. I wonder if it could have to do with anything?

You can run the machine with the cab in the air.
As for the switch, you could cheat by turning the ac on and jumping power to the compressor. If it gets cold the problem is electrical, if it doesn't, its a gas issue.
I tested this with my machine. Ran it and jumped the clutch for the compressor and held the hoses, one got icy cold, the other hot.

 

[OldMachinist]

You can run the machine with the cab in the air.
As for the switch, you could cheat by turning the ac on and jumping power to the compressor. If it gets cold the problem is electrical, if it doesn't, its a gas issue.
I tested this with my machine. Ran it and jumped the clutch for the compressor and held the hoses, one got icy cold, the other hot.

The T300 A/C system when completely discharged holds 2 lbs of freon. The pressure readings will depend on the ambient temperature. As a general rule if the temperature is 90 the high side should be around 235 psi, at 80 its 200 psi.

 

[mrfixitpaul]

The T300 A/C system when completely discharged holds 2 lbs of freon. The pressure readings will depend on the ambient temperature. As a general rule if the temperature is 90 the high side should be around 235 psi, at 80 its 200 psi.

To make sure that the temp dial is working while it may feel loose, turn to low temp and run the engine, feel the heater hoses and see if the coolant is flowing hot.....or have someone turn the dial and watch the coolant control valve (connects inline with the heater hoses, behind cab) to see if it rotates. Engine doesn't need to be running, but key needs to be on for valve to function.

 

[gixxer600]

To make sure that the temp dial is working while it may feel loose, turn to low temp and run the engine, feel the heater hoses and see if the coolant is flowing hot.....or have someone turn the dial and watch the coolant control valve (connects inline with the heater hoses, behind cab) to see if it rotates. Engine doesn't need to be running, but key needs to be on for valve to function.

Thanks guys! I am going to give him all this info and will report back! Craig