Diagnosing my AC on my 2004 Honda Accord Lx 2.4L

[Erik Slow]

I got a new car a few moths ago and I got it without making sure that the AC worked well. I’m not sure if when I checked it, it worked then and then it stopped working or it never worked all along. Anyhow, my AC does not blow very cold air. I checked the levels in the system with a set of manifold gauges and it seemed like the system was full. The ac compressor was not coming on before I checked the pressure oddly enough. I have check relays and fuses. All tested out good. I guest my next stop is to take a look at the pressure in the system again and make sure my readings were correct. Does anyone have any suggestions on where to go next on diagnostics?

Topic

[college man]

see if this helps.

http://www.ericthecarguy.com/faq/solving-automotive-hvac-problems

[Larry Bible]

Rik,

When posting a/c questions it is immensely helpful when you post ambient temp, vent temp and both high and low pressures. It makes it much easier for us to help you.

[Erik Slow]

Thanks MBDiagMan!

Here are some numbers:

Ambient temp – 59 Degrees Fahrenheit
Humidity – 68%
High Side 25 PSI
Low Side 26 PSI
I am not or sure about the vent temp but it felt like it was the same as the inside of the car or outside. My thermometer will not work. I need to get a new one.
The A/C clutch does not come on.

I hope this is enough info! Thanks!

[Bluesnut]

Those pressure numbers are way too low. With the engine and the A/C off the system static pressure equalized should be around 120 on both high and low sides.
The compressor will never cycle on with 25 PSI in it. Sometimes you have to jump the pressure switch to manually engage the compressor until the system has inhaled enough refrigerant to keep the pressures up and the compressor to engage.

[Erik Slow]

Well it looks like its time for the next step. I need to get enough refrigerant in the system with some UV die. Would it be safe to go ahead and add refrigerant without evacuating the system or might that be harmful due to potential moisture in the system from the leak?

[Bluesnut]

An A/C system should always be evacuated before recharging from empty. There are 2 reasons for this.
One is that the moisture can turn acidic when mingled with refrigerant oil and harmful to the compressor.
Two is that any moisture in the system can freeze up quickly (usually around the expansion valve or orifice tube depending) and cause the system to become inoperative; at least until it thaws out.

A system that has air mixed with refrigerant will not be as efficient as one that has had a vacuum pulled on it.

[Larry Bible]

Sorry for the delay getting back to you Erik. Luckily, you have gotten some very good and accurate replies.

Evacuating the system before charging is an absolute necessity, not an option. Also as pointed out, you will have to reach static pressure so that the low pressure switch will complete the clutch circuit. Otherwise it will not engage and start the compressor. If you don’t have a vacuum pump, you can probably buy an old refrigerator compressor somewhere for five or ten bucks, solder a fitting on the inlet side and you have a vacuum pump.

Keep working at it and post your question and pressures as you go. We’ll get you through it.

Hope this helps.

[Author]

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