TN75 air conditioning

   / TN75 air conditioning #1  

musselmark

Silver Member
Joined
Aug 8, 2012
Messages
136
Location
grand tracadie PE
Tractor
'05 NH TN75DA
TN75 da AC problem. No cold air, quickly depressed shrader valves to see if they had pressure and they do. If I turn on AC the compressor will engage and run. If I increase engine speed the compressor will squeal and then sometimes stop turning although belt is still turning clutch sheave. It's like clutch squeals then lets go. If I idle down it will start spinning again and no squeal. Thanks
 
   / TN75 air conditioning #2  
it's normal for the clutch to engage/disengage at higher rpms, since the thermostatic valve is sensing freezing conditions and turns off the clutch, then when it gets warmer, it turns on the clutch. maybe you are not getting enough air over the evaporator, that's one cause. are any AC lines getting cold??.
 
   / TN75 air conditioning
  • Thread Starter
#3  
I will check the lines today. What about the squealing from the clutch at high rpm? Also curious what the adjustment knob for the AC does in the cab, does it just control the periodic engagement of the AC clutch? Colder= longer engagement cycles? Where is the evaporator, is it in the cab, there is lots of air flow coming out of the ducts.
 
   / TN75 air conditioning #4  
Attempting to diagnose A/C problems without service gauges is a waste of time. Yours and ours. Squealing from the fan area can indicate a loose belt. The A/C belt drives off the fan/alternator belt. Check both.
 
   / TN75 air conditioning #5  
First be sure your coil is clean in front of the radiator and also the cab filters are. The evaporator coil is probably in the top of your cab. Check your manual or ask dealer where the cab filters are. But if you have had this tractor for a while as it seems you will need new air filters.
 
   / TN75 air conditioning
  • Thread Starter
#6  
High pressure line is very very hot. Low pressure is not cold just room temp. I removed cabin filter, no change. Condenser coil in front of radiator is clean.
 
   / TN75 air conditioning #7  
High pressure line is very very hot. Low pressure is not cold just room temp. I removed cabin filter, no change. Condenser coil in front of radiator is clean.
then it's most likely low on freon.. you need someone with gauges, and the skill at your tractor to diagnose this!..
 
   / TN75 air conditioning
  • Thread Starter
#8  
Thanks. So those do it yourself kits at auto parts stores are not worth trying?
 
   / TN75 air conditioning #9  
Thanks. So those do it yourself kits at auto parts stores are not worth trying?
the problem is, if you put too much freon in, you can cause damage. a skilled person could use one of those kits and put just enough freon in to make it work properly.. I like using the manifold gauges to monitor both the low side and high side. when I get to 20 deg. F. on the low side, that's good.. making sure the high side is not going too high from a possible blockage.. the gauges are refrigerant specific, BTW,. you need to match the scale on the gauges to the refrigerant used in your tractors AC.. it could be R134, but check..
 
   / TN75 air conditioning
  • Thread Starter
#10  
I just thought of something else. The headliner is all stained and has been getting worse. I assumed it was a leak in roof but could it be condensation from evaporator. Could this have anything to do with my problem.
 
 
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