Ok, Let’s check the pressures in this Air Conditioner.
This is: How to check the “freon” or refrigerant pressures of an air conditioner
Alright, you ac home repairman, here’s where ac repair becomes fun. I’ve been doing this for 20 years here in Las Vegas and let me say, “Putting gauges on a machine and knowing exactly what’s wrong is a gift that will make you professionals quicker and beginners ahead of the game”.
Here, I will explain how to determine a home ac systems desired suction and head pressure and how to compare that to your real pressures to determine how efficiently your system is running or what’s wrong with your air conditioner, just by checking the refrigerant pressures.
(Note: This is a very touchy step and can miss-lead the un-experienced ac technician so follow close and be sure you’re taking every step as follows. This next step covers 99% of all refrigeration issues. If you have more than one major refrigeration issue that may become a bit more involved.)
If they are not already on, hook up your digital refrigerant gauges to the air conditioner.
Now take a thermometer and place the sensing bulb 6” in front of your condenser coil and record the temperature. That is your ambient temperature.
Now simply scroll through your digital gauges settings until they display saturation temperature, that is the temperature of the refrigerant inside the condenser coil. And we call it the head pressure.
The head pressure should be 20-30 degrees over the ambient temperature. If the head pressure is less that 20 degrees over your ambient temperature then that is a low pressure
(Note: add 25-30 degrees for old systems and add 20 degrees to new high efficiency systems of 12 seers or more.)
Your desired suction pressure is 33-48 degrees or 58-80 psi depending on the indoor temperature.
(Note: The hot or warm air from a hot house traveling across the evaporator coil will warm the refrigerant faster than normal causing a higher suction pressure. So, if your home is warm expect a suction pressure closer to 80 psi.)
Now that you know how to get your desired pressures for your air conditioning unit, let’s compare the desired pressures to the actual pressures.
Is your Suction pressure Low Normal High
Is your head pressure Low Normal High
Click on the appropriate link that matches your situation. You Have 5 options.
1. Low Suction & High Head Move to page 19
2. Low Suction & Normal Head Move to page 20
3. Low Suction & Low Head Move to page 21
4. High Suction & Low Head Move to page 22
Because, there is only one reason for having high suction pressure and a low head pressure, “Bad Valves in the Compressor”.
5. Normal Suction & Normal Head –
Then your system is working period. If there was a problem anywhere it would reflect in the pressures. Good pressures in an ac unit mean it will blow cold air inside. But we don’t leave it at that. We charge to perfection, so flip through the digital display on your gauges until they display super-heat and sub-cooling.
Your pressures are good so your super heat and your sub-cooling will be pretty close but dialing this in tight is what will make this system last for as long as it can.
Your desired superheat and sub-cooling is 10 and 10
(Note: Adding Freon will lower superheat and raise sub-cooling…….Removing Freon will raise superheat and lower sub-cooling)
Now add or remove refrigerant to achieve as close to 10 and 10 as you can, as long as you do not let either side get beyond 5 and 20 degrees.
Once a superheat of between 5 and 20 degrees is achieved you are done charging and I’m sure you have done a great job, or you would not be rewarded with anything close to 10 and 10 degrees.
You’ve made it this far, just one more step click the box below to go to the end test where well see if it works or not.