1999 5.9 AC problem

[Josh #15]

1999 5.9. Having issues with ac. When started the ac blows cold at idle and while driving. Once the engine gets to 190 degrees ish the ac will start to blow hot. The only way to get the ac to blow cold again is to get on the gas and it will start blowing cold agin. Another thing when I’m pulling my 30ft camper the ac doesn’t act up like it does when not pulling….. Sooooo. Idk. I did put a new clutch fan on and had the ac recharged. Thanks for any info.

 

[SAndreasen]

Plugged condenser?

 

[Joe Mc]

Look from the top between the rad & condenser use a flashlight. If your 99 still has "just" the stock timing cover vent hose what happens is the oil mist exiting the hose gets sucked into the cooling air inlet for rad/condenser and collects on the back side of condenser and front side of rad, dirt sticks to oil and insulates/reduces air flow thru. Simple fixes:
1- from the 1" gap up top spray non-caustic degreaser such as simple green or the orange stuff cut 50/50 should do it, with rad hot, on both rad/condenser, let it soak for about 5 minutes or so, repeat with degreaser and start engine letting it idle, using a garden hose with no nozzle (don't want pressure to fold fine over/closing them off...) hose it from the outside in and then as best you can from the top gap. Lather rinse repeat till they're both nice and clear of schmutz.
2- get a ¾" coupler, can be plastic, and add more hose to either extend down or, what most folks do myself included, run a length of the hose along the frame to transfer case skid plate, if 2wd somewhere around end of transmission. Be certain that if you run hose along the frame to somewhere around trans that the hose all runs downhill. You don't want any high areas that'll collect oil and create a trap of sorts, best to have that crankcase ventilation clear.
I did this to mine many, many years ago and check for dirt on rad/condenser every spring and just for good measure I clean anyway. Remember you also have the intercooler that'll get dirty to and cause air charge to become not as cool...increasing egts...
Hope this helps.