Help with A/C!

[HighBall]

My a/c was working fine untill it started to work off and on, and eventually it didn't work at all. I got the system checked, and the shop said that there is no leaks, and I have a pound of freon, but the compressor wasn't kicking on. The compressor was kicking on sometimes, but now it doesn't at all.


I bought one of those $20 cans of R134A recharge kits, and the pressure guage read 110 psi!!

I have no idea what to do.

 

[projectSHO89]

Fix your A/C clutch.

There were seemingly dozens of threads about this exact problem back in early summer.

PS There is no need to start a new thread. it helps if you stay in your original one.

Steve

<small>[ October 24, 2003, 03:57 PM: Message edited by: projectSHO89 ]</small>

 

[HighBall]

alright thanks, I just thought that it was two different topics.

I removed my battery, but the battery tray won't come out because of a rusted bolt on the bottom. I couldn't remove the bolt on the clutch because the compressor kept turning. I just beat on the the clutch, and put my battery back in.

My clutch works now!, and the air is colder than usual, but it's still warm. Im not sure if it is working right, here's what it does.

The psi rises between 15, and 45 psi. When the psi hits 45, the compressor makes a click, and then clicks off after 1-2 seconds. When the clicks happen, the psi drops to 15 psi, and then rises and repeats, can someone explain this to me.

 

[projectSHO89]

The way it is supposed to work:

Static pressure is normally above 70 psi. In hot weather with a hot engine, it usually exceeds 100 psi on a fully charged system.

When the compressor clutch engages, the pressure should start dropping.

Depending on a number of factors (ambient temp, state of charge, cycling switch adjustment, system efficiency), the pressure should drop to as low as 20-25 psi at which point the cycling switch opens. Upon the opening of the switch, the clutch disengages and the pressure starts to rise. When the ascending trigger point is reached (usually between 55 and 65 psi)the cycling switch closes again and the cycle repeats.

In very hot weather, the pressure may not reach the low point to cut out the switch, so the compressor will continue to run. Under these conditions, this is normal.

Rapid cycling of the switch (cycle takes less than 10 seconds) indicates that the refrigerent charge is low. If the charge is really low, the clutch will cyle very rapidly (once every 2-3 seconds).

The clicking noise you are hearing should be the clutch engaging and disengaging.

Hope this helps.

Steve

 

[HighBall]

it helps alot, thanks. If ammount of freon, and pressure are separate, then how do I know how much pressure to put in the system, and how much freon to use, and how do I know if it is low??

Also, the most important, how do I know how much freon is in the system?

Sorry if these are stupid questions.

<small>[ October 25, 2003, 03:16 AM: Message edited by: HighBall ]</small>

 

[SHOPWR]

when the compressor kicks on the lowside should drop to 25 low side and high side should be 100 plus ambient temp. you can see how much presure is in the system by using a manifold gauge set. if you should buy a set do not buy a cheap set, i know a guy who bought a cheap set and it didnt read the same as a expensive but accurate set. you could also make sure your high side switch is hooked up. i have made that mistake on a customers car. so i plugged it in and it started cycling as it should and i got COLD air instead of cool air.

 

[projectSHO89]

HighBall
it helps alot, thanks. If ammount of freon, and pressure are separate, then how do I know how much pressure to put in the system, and how much freon to use, and how do I know if it is low??

Manifold gauge set. Add refrigerant (for an undercharged system) until both the low and high side pressures are in range for the ambient temperature. If it is undercharged, your pressure readings, especially the high side pressure, will be out of range.

Also, the most important, how do I know how much freon is in the system?

The only way to know absolutely is to extract and weigh it. Impractical. Experienced A/C technicians can infer approximately how much of a charge is required based upon readings as above and their experience as to how much of a charge had to be added to other vehicles in the past to achieve proper operation. System capacity should be on a label under the hood (if it is still there).

Sorry if these are stupid questions.

They're not stupid. They simply indicate that you are very curious as to how the system works and that you are just starting to learn about it.

There are books available that explain the principles of A/C operation and provide troubleshooting assistance. I purchased a generic Haynes from AutoZone a few years back when I made my first foray into an A/C system. It was very helpful in understanding the basics of the system.

Steve

<small>[ October 25, 2003, 09:24 AM: Message edited by: projectSHO89 ]</small>

 

[HighBall]

I decided to go ahead and charge my system. I used about 3/4 can which was 19oz, with 3oz of oil, and seal treatment.

It is about 85-90 here in FL, and pretty humid. With the car off, and warmed up, the low pressure side reads 90psi. With the car on and the max AC on, the guage reads 25psi, and doesn't move. The clutch just spins and spins.

Am I overcharged? Isn't it supposed to read 100 psi with the car off?

"Add refrigerant (for an undercharged system) until both the low and high side pressures are in range for the ambient temperature. If it is undercharged, your pressure readings, especially the high side pressure, will be out of range."

I only have a low pressure guage, and what is "ambient temperature"?

Your help is GREATLY apprecaited

 

[rangerj]

Highball,

You can borrow a set of gauges from Auto Zone (most) for a deposit. It is important to know what both the low and high side pressures are in order to determine if the system is operating properly.

If the system is cycling refrigerant through the system properly the low side pressure will be about 50psi, and the high side pressure will be about 250psi in "normal" ambient temperature ranges.

You can safely add refrigerant until you get the pressures into those ranges.

Ambient temperature is the temperature surrounding the system, that is "under hood temperature".

The max amount of refrigerant in the Taurus is about 36 ounces. If you have to add refrigerant then you have a leak somewhere.

An A/C system is a sealed system and the refrigerant is not "consummed". The only way it is deminished in the system is by a leak.

Look at all of your connections for a black oily dirt. This is the sign of a leak. Look behind the clutch coil and/or pulley for a compressor seal leak.

Some leaks are so slight that a re-charge will last a year or two. If a shop could not detect a leak, your leak is probably very slight.

If in fact you do NOT have a leak, and you are getting abnormal pressure readings, then you have an internal problem in the system.

Check the gap between the clutch surfaces for about .035.

With out knowing more about what your low AND high side pressures are doing it is impossible to do any further diagnostics.

As Steve said in so many words "there is no such thing as a dumb question". We are all ignorant to some degree, some of us more than others.

There are on occasion dumb answers. I just did one yesterday. I engaged the keyboard without putting the brain in gear! shrug STUFF Happens! rangerj