Several Tips to Help You Know better about Manifold Gauge Set

How many parts does the manifold gauge set include? What should I do to connect all the parts together? What should I do to pull refrigerant into my air conditioner by myself?......Have you ever encountered such problems? The answer for most people with cars must be yes. That is because, it has become a fashion to recharge air conditioner by ourselves over these years. Most of people choose to exchange refrigerant at home to save money rather than go to the car repair shop. In this way, That's where the manifold gauge set comes into play. In order to help people get better understanding of manifold gauge set , we create this FAQ to provide some explanation and hope this will be useful for you guys.

What does a set of Manifold Gauge Set should include？

A picture is worth a thousand words.

How to connect all parts together?

Normally, the manifold gauge set has three hoses with different color ( blue, red and yellow). The blue one is for low pressure service port, while, the red one is for high pressure service port. The yellow one in the middle is connected with refrigerant cylinder while charging or the vacuum pump when the system is being evacuated of air and moisture.

Functions of high & low pressure valve

How to add refrigerant into air conditioning system？

Below is a video link for you to study about how to pull refrigerant into air conditioning system.

https://www.youtube.com/watch?v=Pdq8JAlct6s&t=2s

Based on this video, please pay much attention to below points when you start to pick up suction:

1. After 15 minutes of continuous pumping, when the vacuum degree reaches -30inHg(7.6mpa), we need to close the high/low pressure manual valve and observe the pointer of the low-pressure gauge. If the pressure rises, it indicates the system leaks, and then you need to charge vacuum into the system after repairing the system;
2. If the pressure does not change, please open the high/low pressure manual valve and the vacuum time shall not be less than 30minutes.

Factors leading to leakage

1. The system is not full of vacuum before you charge refrigerant into air conditioning system;
2. There may some leakages in the car pipe;
3. After draining the vacuum, high/low pressure valves should be closed firstly and then the vacuum pump, otherwise, pressure backflow may cause leakages.
4. The connections of the set is not tight enough or the seal ring is broken;
5. Expansion valveof the air conditioning system is broken.

How can I tell the system is under vacuum? （Updated on 20th, Aug, 2021）

Close the high/low pressure manual valve and observe the pointer of the low-pressure gauge when the vacuum degree reaches -30inHg. If the pressure does not change, then we could believe that the system is occupied with vacuum.

-Don't forget to run the pump for another 30 minutes to ensure the system is completely clean, no moisture or air left.

How can I tell refrigerant leakage?

Normally, it is easy for us to find refrigerant oil from the place where there is a leakage. If oil is found to be leaking from a location, it can be further wiped with a clean white paper. If oil is still coming out, there may be a leakage.

How can I tell the expansion valve is bad?

Below points will give you a huge favor on this issue:

1. During operation, if the low side pressure is much higher than normal low pressure and high side pressure is slightly higher than normal high pressure, there must be something wrong with the expansion valve.
2. During operation, just opposite to the first point, if the low/high side pressure are both lower than normal low/high side pressure, the expansion valve must be a defective one.

How can I tell the compressor is bad?

Basically, if the low side pressure is much higher than normal low pressure, while, the high side pressure is much lower than normal pressure, we could confirm that there must be something wrong with the compressor. The usual sign is that we need to take longer time to feel cool no matter how substantially we increase the speed of the engine.

How can I tell the orifice tube is clogged?

In the process of operation, if it takes less time for the compressor to cycle out and the rise in suction side pressure is very slow , then we could confirm that orifice tube is clogged.

How to return the pressure gauge to zero when the pointer is not at zero?

The zero adjustment screw on the gauge could just work out this issue. All you need to do is just twist the screw to zero.

How to recycle old refrigerant before vacuum?

Only 4 steps will drag you out of the dilemma:

1. Close the high and low pressure manual valves and connect their high and low pressure hoses to the high and low pressure maintenance valve of the The hose in the middle needs to be put on a piece of clean cloth;
2. Slowly open the high pressure hand valve and allow the refrigerant to drain from the middle We just need to slightly open the valve, otherwise, the refrigerator oil will flow out of the compressor;
3. When the pressure gauge reading drops below 0.35MPa, we need to slowly open the low pressure manual valve to allow the refrigerant to flow from the both high and low pressure side;
4. Observe the reading of the pressure gauge. As the pressure drops, we need to gradually open the high/low pressure manual valve until the reading on the high/low pressure meter is zero.

Warm tips

1. When the refrigerant is being filled from the high-pressure side, both the low-pressure manual valve and the air conditioning system must be in the closed state;
2. When the refrigerant is being filled from the low-pressure side, the high pressure manual valve must be in the closed state;
3. Remove air from the middle yellow hosewith valve core wrench every time you change the refrigerant tank;
4. During the filling process, the cap and the bottom of the refrigerant can should not be placed on people to prevent explosion in case of improper operation;
5. Please do wear gloves and goggles to protect yourself during operation.