Skip the auto shop - Our mechanics make house calls

Q: AC Compressor Runs All the Time With No cooling in Cab

asked by on

2006 Dodge Ram3500 5.9l Cummins Diesel Laramie 151,000mi, Replaced 2 weeks ago, Condenser, Evaporator, Receiver/Dryer, Liquid Line (Orifice Tube). Added 7.1 ounces of PAG Oil/OEM Spec to to (Accumulator, Condenser, Evaporator and Compressor) system. I removed the dash and replaced the Evaporator and Heater Core as preventive measure. Inspected all HVAC doors and servo-motors all SAT. Pulled vacuum for 2 hours with no leaks. Added 30 ounces of R134a freon per OEM spec. and cab temperature was at 47f. Now cooling failed again and measured no pressure in system with compressor clutch engaged spinning when AC switch is on? There is only one pressure switch with this design. Compressor replaced June of 2015 <1yr old (Remanufactured from Chrysler/Dodge). Suspect pressure switch at fault and or compressor fault?

My car has 999999 miles.
My car has an automatic transmission.

A: If you are measuring no pressure in the sys...

If you are measuring no pressure in the system, then you have a leak and will have to find where the leak is. If you don’t have a leak detector, then you should obtain one or get a professional with the correct tools to help you. You may have a connection that is leaking or the compressor is leaking out of the front seal if you do not find any leaks then this is the most likely place to look and listen. If oil was added with dye at the last A/C service, then you can use a black light leak detector with yellow glasses. You can get this at most any auto parts store. If you can’t find the leak yourself or don’t have the correct tools, you should contact a professional, such as one from YourMechanic, to diagnose the a/c problem for you.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: How do I check the tire pressure?

You can check the tire pressure for each individual tire using your car’s electronic vehicle information center (EVIC). The EVIC display screen is located in the middle of the gauge cluster, and gives the driver lots of pertinent information. The...

Q: Loud air conditioner noise

Do you hear the noise with the engine running and A/C off as well? If not, your problem may be the A/C compressor clutch or the bearings in the belt driven compressor pulley. If you always hear the noise while...

Q: Clinking sound in frount axel

Based on what you have described, I would agree that a problem with the axle is the source of the clicking noise. However, it could be a wheel bearing problem that is causing this noise. In order to know for...

Related articles

How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.