backdoc4you

2007 GL450 with 140K miles on it. I'm learning to take care of this vehicle myself as the cost of bringing it to the dealership with every problem would lead to bankruptcy
My AC will blow ice cold when I'm driving down the highway or when engine RPM's stay up at 2000 or higher. Then when driving it from light to light, I smell an odd smell and it starts to blow warm.
Any thought or ideas as to where to start looking? Thank you so much for your opinions and knowledge!

gl450x164

your aux fan probably isnt working

alx

and aux fan is not working because he is low on charge. at his mileage and age that is very common. recharge. if low again inject dye and look for a leak.

gl450x164

i wouldn't necessarily jump the gun and say low on charge as he said it works when he is moving and not when he is stationary, i have never had this issue on mine and im at 170k but you see these alot more than i.

alx

low rpms - low pressure - high rpms - higher pressure. low charge - low pressure. low charge + low rpms - insufficient pressure.

attach manometer on low side shraeder valve. turn on ac to max. i bet donuts to dollars he will not see sufficient pressure - 35-40 psi at 70 degrees ambient.

backdoc4you

Thanks you guys! Both of these make sense and give me something to work with. But yes....freezing cold when vehicle is continuously moving along.
Much appreciated! I will keep you informed.

alx

you will also notice that turning the ac to max will not turn on the aux fan. once you recharge system the fan will turn on.

Callisto1

Alx is the resident guru, so his advice is certainly sound. However, I once had a similar problem and the dealer spent days trying to diagnose it (thankfully under warranty). In the end, it turned out to be a loose ground wire. Somehow at high speed it made contact, maybe because of the vibration from the road. At idle, it sometimes made contact but not always. Easiest fix in the world, but it was hell to diagnose.