I have replaced orifice tube, drier, cleaned out evaporator and condenser. new filters vacuumed out system and new refringent still cant get the vent temp to go below 60 degrees
Dustin- Would be more than happy to advise, please respond with the following information. -Machine serial number prefix -AC pressures (high side and low side) at idle and high idle -Ambient air temperature -A little bit of history leading up to this issue -How much R134a was put in the system during recharge
Hello and thank you. the ser number prefix is kmm low side pressure is 50 at idle high side is 250. I have not checked at high idle ambient temp 90 degrees the ac would blow cold in the morning when the ambient temp is around 70 degrees, but once it got past 80 outside the vent temp would be lucky to get below 70, so i put new filters in cleaned the condenser and evaporator. Both fans are working, Compressor is working and still the same results. So I replaced the drier and orifice tube, vacuum out the system and added 3lbs of freon. Now vent temp is a consistent 60 degrees so it's a bit better but I checked vent temp of our other machine's (one being same model and year dozer) all are blowing between 40 and 45 degrees out the vent
Where'd the 3# spec come from? The pressures and the "3#" sound very high.
Spec is 2.9Lb per sis web.
call cat and thats what they told me
check that the heater control is working correctly turn off the heater taps on the engine to confirm
ill look into this. do you know where the taps are located?
I don’t believe they are heater valves on your engine. You can clamp off one of the hoses to stop any flow going to the heater core.
I really have nothing to offer in this discussion except it makes a big difference in the A/C with the heater valves off on our D5G and 953C. Sometimes I'll forget to turn the valves off when the weather turns warm and think we have an A/C problem.
Blend door seems to be working fine
I, personally, think the charge level is too high. I just replaced a compressor on a 314ELCR, and the machine sticker for charge amount was different than the book. The book was higher. I'd like to see no more than 40 psi on the low side, at idle, on an 80° day. At fast idle, when I don't have a charge spec, I try to make sure it doesn't drop below 25psi on the low side. All of my late model Cats do have a charge amount sticker somewhere on them. Any chance of throwing the gauges on the twin machine you have?
As ahart mentioned above there are no heater shutoff valves I can see on your machine, just two spigots for the heater line connections. See illustrations below. however I suggest that you check those locations physically just to make certain. However as a test why not try crimping one or other of the heater lines from the connections at the engine to the cab using a pair of vice grips. That will stop the flow of hot coolant from the engine totally. If the A/C then performs correctly you should start looking at the operation of the electric heater valve located in the heater assembly as mentioned by Mark250 in Post #7 above.
50psi on the low side will never cool sufficiently.
I agree heymccall, I think 250 psi on high side is excessive, needs to be closer to 180. If you get the high side down, the low side will probably follow.
Off idle High idle
Those pressures look pretty good, what’s the vent temp?
42 in the morning after lunch 72-75
Are pressures always what you sent? Morning and after lunch?
Does that machine have the condenser on back of cab like a track loader. Have seen lots of 953,63, & 73's with bad fans cause lots of issues.
Those readings I sent where from this morning. Last time I checked them in the afternoon they where higher low side was above 50 high side was almost 250
this is the very first thing I check on AC issues for these machines that have that condenser package setup. Very common to find one or both fans shot, usually seized up. One wore out loud one can sound like both are blowing properly.
Have a 963C at this very moment with bad fans. They ran it last summer with a straight stack on it so all exhaust was going up through condenser and fans. They were renting machine last year and did not want to spend much money on it but bought it over winter. Wanted me to fix A/C this year and found fan completely melted into condenser from exhaust heat lol. Can't fix stupid but sure can charge for it.
Your not cooling the condenser efficiently. Check the fan operation and the cleanliness of the core as some have suggested.
both fans are running sounds like the same speed and first thing I did was cleaned out the condenser was jam packed full of dirt and leaves so thought for sure once I washed it out it would fixed it. It helped but didnt fix it
Let’s check the evaporator temp and compare it to vent temp. It’s also possible condenser could need replaced. Need to do a temp drop on inlet and outlet just as you would on a radiator to check efficiency.
What temp delta do you look for on condenser and evap inlets and outlets?
You do have the vent system set on recirc….correct?
So I checked the drop across the condenser on a 740B with an AC system that is functioning very well considering temps. 84 degrees outside and direct sunlight, 46 degree vent temperature. Inlet to condenser is 136 degrees and outlet is 104.