Air conditioning problem

[bonneau1]

My ac works fine and blows cold air while at idle, but when I drive the ac blows hot air like my compressor is not working I asking for anyone that has has this problem on what I should check . it is a 91' infinti q45
Modified by bonneau1 at 6:07 PM 3/26/2008

[maxnix]

What year? Please complete your profile so that we may help you.

[qship96]

Any accurate diagnosis begins with confirming proper freon level, which can only be accomplished by a leak test & evac/recharge procedure

Once this is completed properly, further testing and troubleshooting if required becomes easier and far more accurate.

[qsiguy]

Ok, lets be realistic. Most people aren't going to dive in and do a full leak test, evac and recharge to do some simple checks. I fix a/c all the time for my own vehicles and others. If you don't have at least a manifold gauge set I wouldn't even bother trying to fix it on your own. You have to know the high and low pressures to do anything.

I/we do need some more detail/history as Maxnix said. What year Q? Have you been working on it and now this is happening or did it just start doing this on it's own? My first thought would be that maybe you just recharged it and got too much freon in it. There is a hi/low dual pressure switch that will kill the compressor in the event of to little pressure or too much pressure.

If you want any more detailed help provide some more information.

EDIT: Ok I see that it's a '91. How about some history? Have you been working on it? Has it been out for a while? Has it been working and just stopped?

[qship96]

Shortcuts in air conditioning diagnosis and repair frequently lead to mis-diagnosis, unnecessary parts replacement,multiple shop visits, and sub-par results

Anyone not willing to start with confirming proper freon level and condition{lack of moisture, and system leaks} by investing in the evac/recharge procedure as a prerequisite deserves the headaches that will likely persue.

Tons of owners and half-*** mechanics create more problems and prolong proper diagnosis by taking shortcuts when it comes to A/C work, which is surprising as the refrigeration cycle is pretty basic and similar on all cars, and has been around for about a half- century

[qsiguy]

I understand your point and where you are going with this but...

There is nothing half-*** about troubleshooting the system without wasting the whole freon charge and spending hundreds of dollars for someone to do it only to later find out it was a fuse or defective switch. There are many areas of the a/c system that can cause problems that have nothing to do with the freon level or a leak. So you are saying that the first thing you personally do every time you have an a/c issue is run down to your local Q45 mechanic and have him check for leaks and suck out all the freon, vac, and refill it? That's rediculous, honestly. There are many electronics, relays, fuses, controls, etc. that could just as easily be the issue.

I guess everyone has their own beliefs of how things should be done. There is no harm in checking pressures on the system and they will tell you a lot. If a mechanic were to dive in and evac and recharge an a/c system without at least checking things out first it would be my opinion that they have no idea how to properly diagnose an a/c system and they would never work on my car. There are far too many mechanics these days that don't know how to troubleshoot at all.

[Q45tech]

Unfortunately the pressure readings are only valid and useful, IF YOU KNOW THE EXACT WEIGHT OF R12 CHARGE!

[maxnix]

Unfortunately the pressure readings are only valid and useful, IF YOU KNOW THE EXACT WEIGHT OF R12 CHARGE!

So true, so back to evacuation and recharge. Might try a little sniffer for leak detection so he has an idea of what to replace.

[qship96]

Unfortunately the pressure readings are only valid and useful, IF YOU KNOW THE EXACT WEIGHT OF R12 CHARGE!

Why is this such a hard concept for many owners and a/c service Mechanics to grasp? It all begins with proper leak detection and evac/recharge to exact weight.

Any monkey that advertises "top off" of a/c system using gauges and a tank of refrigerant is either incompetant or a crook looking to make a quick buck.....you will start to see their calling cards{signs} pop up in front of gas stations and service shops now as the weather turns warm-RUN LIKE HELL from one of these services.
Modified by qship96 at 4:16 PM 3/27/2008

[Jesda]

In addition, R12 is NOT CHEAP (if you can even find it). The last thing you want is for it to continue leaking. Imagine having a safe full of gold coins... with a giant hole in the bottom.

After this long with most likely original hoses, I'd bet my life on there being a small leak somewhere.

[DrewQ45]

Any accurate diagnosis begins with confirming proper freon level, which can only be accomplished by a leak test & evac/recharge procedure

Once this is completed properly, further testing and troubleshooting if required becomes easier and far more accurate.

I agree totally. Just a full vacuum and recharge alone might resolve the problem if air pockets are to blame. Have someone vacum it down overnight as a leak test.

[dosborne]

You say shortcuts, I say save for the pumps I don't know about others on this forum, but I am attending school and appreciate the "shortcuts" as I am fortunate to have an Infiniti, just not "fortunate" to be able to afford the proper, recommended advice you so kindly offer. If I could afford to take my car to a master technician such as your self, I could afford to say "fill it up".