Climate Control Systems Service Topics covered in this presentation: Gauge set and refrigerant Service ports and valves Discharging, evacuating and recharging

Introduction The hot part of the a/c system has high pressure. Warm The cold part of the system has low pressure. Faults can occur making the pressure too high or too low. Cold Cool Pressure tests (using the service ports), can be made to help determine faults. Next >

Question 1 The cold side of an a/c system has low pressure. Is this true or false? Answer True or False. Correct Answer = T

Gauge Set Gauge set connects to service ports. High pressure gauge Low pressure gauge High pressure gauge Manifold Low side valve High side valve Low pressure hose connected to low pressure service valve High pressure hose connected to high pressure service valve Service hose connected to oil supply tank Service hose connected to charging station Next >

Question 2 Which colour is associated with low pressure on a gauge set? A) Black B) White C) Red Correct Answer = D D) Blue

Gauge Dials High side pressure gauge displays pressure in bar (psi). High Pressure Gauge Low Pressure Gauge Low side pressure gauge displays positive bar (psi) and negative (mm-Hg - vacuum) pressure. Note: Gauge shows 0 bar. Next >

Question 3 Which of the following is NOT a unit for the measurement of pressure? A) psi B) vacuum C) bar Correct Answer = B D) mm Hg

Manifold Flow Control Both valves can be opened or closed for pressure checking. When the low valve is open it allows flow from the low side to the centre hose. When the high valve is open it allows flow from the high side to the centre hose. Both valves open to allow flow from both sides. Next >

Refrigerant Types Two types of refrigerant are typically used in automotives: R-12 & R-134a. R-12 is a CFC and is no longer used in new vehicles (stored in white container). R-134a is an HFC and it has replaced R-12. R-134a operating pressures are higher than R-12. R-134a is normally kept in a light blue container. R-12 and R-134a containers and service port connections are different. Next >

Question 4 Which refrigerant is normally kept in a light blue container? A) R-12 B) R-134a Correct Answer = B

Service Ports R-12 service port has a male imperial service fitting. Male thread fitting Schrader valve To charging station To system R-134a service port has a Quick Detachable fitting (QD). Both types have Schrader valves. R-134a Service Port QD Fitting To system Schrader valve To charging station Service port can be connected to: Charging station. Oil refill tank. System lines. Dust caps must be fitted to the Schrader valves when they are not in use. Next >

Question 5 If you were looking at a new vehicle, which connection system would you expect to see at the a/c service port? A) Male Imperial B) Quick Detachable Correct Answer = B

Inspection Sight Glass The inspection sight glass can be found in the accumulator (drier) or in the refrigerant line. Sight glass It is used to visually inspect the refrigerant. Sight glass will show either: Clear Cloudy Bubbles (Foamy) Oil Streaked Next >

Question 6 Which of the following would you not expect to see in an inspection sight glass? A) Liquid level B) Bubbles C) Streaks of oil Correct Answer = A D) Cloudy

Discharging the System Low pressure valve open High pressure valve open Refrigerant recovery Charging station The refrigerant must be discharged when the system needs to be opened. A charging station (recovery unit) is used to remove refrigerant. The charging station can connect to the gauge set or directly to the low and high service valves. Both valves will be open when recovering the refrigerant. The recovered refrigerant is recycled and can be used to recharge the system. The refrigerant is normally recovered slowly and controlled by the charging station. Next >

Question 7 What is meant by 'discharging' the a/c system A) Removing extra pressure from the system B) Removing excess refrigerant from the system C) Removing all the refrigerant from the system Correct Answer = C D) Removing the gauge set from the system

Evacuating the System Low pressure valve open High pressure valve open Charging station The system must be evacuated when it has been discharged/opened or moisture is in the system. A vacuum pump removes any air and moisture left in the system. Both the high and low pressure valves are normally opened. The vacuum created causes any moisture to boil at room temperature. Next >

Question 8 What is used to evacuate an a/c system? A) A vacuum pump B) A compressor C) A supply of compressed air Correct Answer = A D) A source of distilled water

Recharging the System The charging station is normally used to measure and refill the system with the correct amount of refrigerant. High pressure valve closed Low pressure valve open Charging station The amount of refrigerant to be added is measured by weight (pounds or grams), and is normally found on an A/C label under the bonnet. The high pressure valve is closed, and the low pressure valve is opened. The vacuum draws refrigerant into the system. The system pressures must be checked after charging. Next >

Question 9 When recharging an A/C system, both valves on the gauge set must be open fully. Is this true or false Answer True or False. Correct Answer = F

Possible Recharging Errors Undercharge This occurs when there is not enough refrigerant in the system. It can cause inadequate cooling, faster refrigeration cycle and low system pressures. Overcharge This occurs when too much refrigerant is in the system. It produces inadequate cooling and liquid will not turn into vapour. This causes high system pressures and a constant running compressor. Water Moisture Moisture in the system can cause corrosion. The moisture can freeze causing erratic operation and unexpected system pressures. Next >

Question 10 What causes the liquid not to turn into a vapour? A) Undercharging B) Overcharging Correct Answer = B

Summary You should now be aware of: Gauge set and refrigerant Service ports and valves Discharging, evacuating and recharging End >