a/c not running as cold

[ftexplorer]

I have a 2000 V6 SOHC 4WD Explorer. The a/c has not been running cool on the highest fan setting but not cold. I thought the a/c needed a recharge and bought the EZ Chill can with the pressure gauge on it. The car was hot and outside temp was 90 degrees. The air was on max, and I hooked up the can to take a look at what the gauge said. It was in the yellow zone with a reading of about 55 PSI. So I didn't add any coolant. I'm not sure what to do at this point as I don't have any a/c experience. Some post I read said those gauges suck, but I would imagine it is decently accurate.

What problem could be causing the a/c to run not as cold?

 

[robertoa1a]

The real big question when it comes to ac is, do you understand ac fundamentals enough to be messing with it? With that question asked there are a host of issues that could cause it not to be as cool as it was. It may just be hotter outside. The condenser could have bugs and dirt on it. The radiator could be getting too hot for heat to dissipate from the condenser. It could be the dreaded blend door issue causing heat and air to be mixed. It could be a clogged orifice tube. Someone could have introduced air into the system causing a false high refrigerant pressure level.

How does it work on a cold start with engine cold?

 

[ftexplorer]

I let the engine cool for 3 hours before I had to go somewhere. I turned on the a/c and it felt colder than it did earlier in the day. Where should I look from here, and does the higher pressure on the low pressure valve mean anything?

 

[robertoa1a]

There's a little more to reading gauges than meets the eye. Refrigerant pressure varies greatly with temperature. Starting with the A/C off you can measure static pressure. Both high and low sides should measure equal (at 90deg f pressure should be about 100psi). With the windows down and A/C on high the low side should measure about 1/2 ambient temperature and the high side should measure 2.5x ambient temp (at 90deg 45psi and 225psi respectively). DO NOT ATTEMPT TO ADD REFERIGERANT TO THE HIGH SIDE.

One more thing Is there enough fluid in the radiator?

Does the compressor clutch kick on and off too frequently (short cycling)?

 

[ftexplorer]

I'll need to buy a set of gauges. The low side is on top. Where is the high side located? Also, your PSI descriptions, are they based on a hot engine or cold engine?

 

[robertoa1a]

The low side is on the passenger side near the firewall by the drier tank. The high side is near the compressor. I bought a set of gauges at harbor freight for $40 but you may not have to. Is the compressor clutch constantly kicking on and off while running with windows down on max air?

 

[xplorercrazy]

The PSIs that robertoa1a listed are only slightly affected by engine temp. Outside air temp, the cooling effectiveness of the condensor, and the condition of the compressor are the biggest factors determining you system pressures. Is your fan clutch working properly? Low side connection will be on the dryer and the high side coupler is located on the liquid line between the compressor and the condensor on the drivers side close to the battery.

 

[robertoa1a]

Okay I have a guage like yours yellow is between 45 and 65 psi. Was that with the A/C on or off?

 

[robertoa1a]

X' crazy is right. Assuming the engine is cold and using a baseline pressure to trouble shoot, I'm just trying to get a ball park.

I realize It's not easy one. There are a lot of variables.

 

[ftexplorer]

Okay I have a guage like yours yellow is between 45 and 65 psi. Was that with the A/C on or off?

It was with the a/c on.

 

[robertoa1a]

With the A/C off it should measure about 100 psi at 90deg, well into the red (12:00 on mine). The thing is I live in florida and mine gets cold. So how about the compressor. Does it click on and off (cycle) a lot, Like every 10 seconds or does it stay on constantly when the A/C is on? This is leading somewhere.

 

[ftexplorer]

I finally had a chance to get the gauges from Autozone. Regarding the cycling on, it does not go on and off every 10 seconds. It stays on. The low pressure gauge reads 48 psi. The Haynes manual says 22 - 45 is normal. The high side gauge was broke. It would not lock on and caused some freon to leak, not enough to worry about. It did go to 75 psi but without a tight fit that was probably off. It was 90 outside. Let's say the high pressure was lower than it should be. What would cause that? I'll probably try another gauges set but will have to wait for it to come in.

 

[Dilbert5]

I finally had a chance to get the gauges from Autozone. Regarding the cycling on, it does not go on and off every 10 seconds. It stays on. The low pressure gauge reads 48 psi. The Haynes manual says 22 - 45 is normal. The high side gauge was broke. It would not lock on and caused some freon to leak, not enough to worry about. It did go to 75 psi but without a tight fit that was probably off. It was 90 outside. Let's say the high pressure was lower than it should be. What would cause that? I'll probably try another gauges set but will have to wait for it to come in.

Sounds like you have too much, and as far as charging goes, slightly low will cool better than slightly high, The added pressure will only put more stress on the system components. I charge my personel cars to around 32 psi (while running). As far as cycling goes, it should not be cycling very often, if it is cycling every 10 sec, that is a good indication that it is low on freon. As far as the high side goes, until you get the connector to lock on, forget any reading you see.

Do you have one of those dial thermometers, those are cheap and a good addition to your tool box. I set up my, and my wifes car so that they both are running around 30~34 on the low side, 200 something on the high, getting around 40deg air out of the vents.