Skip the auto shop - Our mechanics make house calls

Q: A/C issues

asked by on

My 2000 Chevy Tahoe has no cold A/C. So I went to the store today and bought an A/C recharge kit to recharge it. It directed me to disconnect the hose and check my level before connecting it to the A/C coolant bottle. So I did this and I immediately realized that it was in the middle of the red zone, obviously meaning it was severely overcharged. I have never recharged this system before, so there should be no reason it is overcharged. But then I realized that when my A/C compressor kicks on, the pressure drops down to the blue, meaning that it is undercharged. It makes no sense that it goes from being overcharged to undercharged. Does anybody know the solution to this or why this would be happening? Thank you for your help in advance.

My car has 135000 miles.
My car has an automatic transmission.

A: When you do not have the A/C on, you will h...

When you do not have the A/C on, you will have pressures on the low and high side be at about 90 to 105 on both sides. When you turn on the A/C with engine idling, the low pressure will run around 25 to 35 and the high side will be 175 to 210. This is normal. If you are using a store bought can, it should be used as a guess for correct pressures. Add a little bit of refrigerant at a time until you feel the A/C getting cold, and the pressure is around 25 to 35 with the A/C blower on the low blower setting. Do not overcharge it. Stop when it is getting cold. If you had to add more than a few ounces of refrigerant, then you have a leak somewhere and should get it checked by a mechanic.

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: The truck wasn't starting up or making any noise. I replaced the starter and it still doesn't want to start up. It just makes a clicking noise

Hey there. You have a bad battery or there is a bad connection in the starting system. The battery should be load tested and the state of charge should be checked with a hydrometer. Your starter requires about ten times...

Q: Rough idle when A/C on

Your engine throttle body and idle air control may be clogged with carbon and engine is idling too low with A/C on causing the rough idle. Have the idle control valve and throttle cleaned out. You may also have the...

Q: I have a wobble on the pulley and an oil leak, is it going to need a main bearing?

Hi there. The two symptoms you're describing (the front oil leak and the crankshaft pulley wobble) are two of the best indicators that a professional mechanic should use to diagnose that the issue is the pulley or the seal behind...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...