Mobile Vehicle Air Conditioning Service Shropshire & Mid Wales
Air Conditioning Mobile Service Engineer specialising in maintenance , repair and servicing of vehicle air conditioning covering Shrewsbury, Oswestry, Shropshire and Welshpool Mid Wales areas .
On-site Air Conditioning Service
Automotive Vehicle Air Conditioning Repairs to Car Van & Light Commercial Ambulance * Minibuses * Motorhome
* Commercial & Fleet HGV Trucks * Coaches *
Tractors & Agricultural
machinery Air Conditioning Regas
Mobile Plant * Excavators * Construction equipment * Quarry plant *
* Marine
FGAS 2079 class 1 trained mobile service engineer travels to you to diagnose, fault find and fix your vehicle air conditioning system Telephone 07703 558610
How Vehicle Air Conditioning Works
Vehicle air conditioning systems function to move heat energy away from the cabin interior keeping driver and passengers cool and comfortable.
Heat energy is transferred (lost) from ambient air inside the vehicle to the evaporator unit which is a heat exchanger. Heat is absorbed by refrigerant during changes in refrigerant state (phase), pressure and temperature.
The vehicle air conditioning refrigerant system forms a circuit.
Refrigerant is pumped around the air conditioning system circuit by a compressor . The air conditioning compressor sucks in low pressure refrigerant gas, raises refrigerant pressure and temperature, and pushes out the refrigerant as a high temperature gas causing flow through the vehicle air conditioning system pipework circuit and heat exchangers. Refrigerant changes (phase) state between gas and liquid at various points in the refrigeration circuit. Super-heating (vapor) and sub-cooling (liquid) of refrigerant takes place due to temperature and pressure changes.
Are the Cooling fans working?
Heat energy is moved by electric cooling fans as hot air inside the vehicle cabin is drawn through the fins of the heat exchanger, where heat transfers to the refrigerant. The air temperature is reduced as heat is lost providing a cool breeze effect.
Vehicle air conditioning systems provide best cooling effect with the cabin interior fans set on full speed and vents set to recirculation mode.
The TXV and the Evaporator
High pressure liquid refrigerant passes through a thermal expansion valve (TXV). The TXV meters refrigerant reducing both pressure and temperature. A controlled amount of refrigerant enters the evaporator gaining heat transferred to the cool flow of refrigerant. Refrigerant temperature increases ('superheat') as evaporation takes place. Problems with the TXV such as a sticking valve or blockage can cause air conditioning to fail, usually best diagnosed using manifold pressure gauges.
The Condenser
Heat absorbed by the refrigerant in the evaporator flows through pipework to another heat exchanger known as the condenser. Hot refrigerant gas loses heat (sub-cools) whilst flowing through the condenser changing state to liquid. The hot condenser exchanges heat to the outside air which is forced over fins by a cooling fan.
The condenser fans are sometimes the same fans as cool the radiator, some vehicles have additional condenser fans. If the condenser fans do not work engine overheating and air conditioning failure may result.
What happens if the air conditioning system loses refrigerant?
If the air conditioning system loses refrigerant it will also lose cooling effect. There are pressure switches fitted so eventually low pressure will cause the pressure switches to disengage the compressor circuit. No compressor operation means no air conditioning working.
Air Conditioner Manifold Pressure Gauge Diagnostics
Understanding the thermodynamic operation of the refrigeration cycle, temperature changes, enthalpy, electrical and electronic controls is important to engineers working on vehicle air conditioning climate control systems requiring technical competence and training which goes beyond the fastfit type automatic air conditioning service machines which are often dedicated to one or two types of refrigerant.
Vehicle Air Conditioning System Benefits
Air Conditioned Comfort - A Fresh Environment
Passenger compartment heat is transported to the exterior allowing travel in fresh, air conditioned comfort.
The Cooling effect of a working air conditioning system protects the driver, passengers, and cargo from excessive temperatures.
Maintains a fresh controlled cabin temperature and reduces transport stress.
Controls Humidity
Purifies & Cleans Air as the evaporator removes small dust particles
Cool Temperature Control
The air conditioning system will only allow maximum cooling if it is fully functional. Blown hot and cold air is blended by vent flaps of the climate control system. A mixture of cool and hot air can be used to control temperature.
Safety, Security, and Improved Work Environment
Air conditioning enhances driver and passenger safety in hot environments by maintaining a fresh and comfortable vehicle cabin temperature.
Air conditioning temperature control reduces
.
risk of heat exhaustion.
Cabin climate control allows windows of vehicles and mobile plant to remain closed reducing noise and dust to improve the driver working environment.
Provision of improved driver comfort reduces fatigue encouraging the driver to remain alert for longer time.
Pollen Filters - Cabin Air Filtration and Purification
Air entering the vehicle interior passes through a pollen filter to reduce dusts and pollution for improved breathing air quality.
Pollen filters are a service item which require periodic replacement.
During AC operation, air temperature reduces as it contacts the air conditioning system evaporator, this also results in a wet evaporator surface which traps particles of dust and pollen.
Improved Vision
Air conditioning dehumidifies air removing moisture.
Dry air helps maintain safety in winter and damp weather conditions by keeping windscreen & cab glass demisted to improve drivers vision.
Security
Air conditioning allows vehicle windows to remain closed in hot weather enhancing security.
Tips for setting air conditioning climate control to achieve best cooling effect : Temperature & Fan Controls :
Keep vehicle windows closed. A functional check of air conditioning controls includes :
Set air conditioner temperature control to coldest
Switch air vent system controls to recirculation mode
Set blower fans to high speed
If your vehicle aircon system is functioning correctly - Enjoy chilled air breeze for a cooler fresh driving climate and more comfortable journey.
Use the vehicle air conditioner all year round
Drivers may be reluctant to use the air conditioning all year round due to fears of increased fuel costs.
Using the air conditioner all year round helps to keep the air conditioning system operational and Windscreens clear of mist.
Faults : Some reasons why your vehicle air conditioning system may not be working
All air conditioning systems require regular servicing.
Does Warm air come out of vents with air conditioning on ?
Vent temperature : Warm air blowing from automotive cabin vents when the air conditioning temperature control is set to cool
indicates that the aircon system needs maintenance repair or service.
When air conditioning is working properly air blown from vents will feel icy cold.
Vehicle cabin aircon vent temperature is best checked using a thermometer.
Refrigerant Loss from air conditioning system components
Automotive air conditioning refrigerant circuits are pressurised systems.
Refrigerant loss may if vehicle air conditioning system becomes faulty due to leaking or corroded pipework, seals, or components.
Air conditioning condenser
heat exchanger can be a common point of failure due to its location at the front of the vehicle and possibility of impact damage.
AC receiver dryer units mounted in areas subject to road spray can be particularly vulnerable to corrosion and leakage. Vehicle vibration or chaffing can cause pipework to fail.
Refrigerant leakage from vehicle air conditioning evaporator is less common but can be difficult to detect and complex to repair because of location behind vehicle dashboard.
Air conditioning refrigerant loss symptoms from a vehicle climate control system may include:
Hissing noise of gas escaping can indicate a refrigerant leak, though most leaks are less obvious. Refrigerant should be recovered from the system as soon as possible for environmental reasons.
Warm air blowing from cabin vents.
Air condtioning compressor fails to operate
Many (but not all) vehicle air conditioner systems use a compressor,
pulley driven by an electromagnetic clutch which you might hear cycling during air conditioner operation with a 'click' on and off as the aircon compressor operates.
Autoelectrical faults or excessively low or high refrigerant pressure sensed by the pressure switch may prevent engagement of the vehicle aircon compressor electric clutch.
Loss of refrigerant can also result in loss of the refrigeration oil which lubricates the air conditioner compressor leading to subsequent failure.
Marginal refrigerant gas loss can occur over time by permeation through hoses. Vehicle manufacturers generally recommend that an automotive air conditioning system has a refrigerant recharge every two years.
Air conditioner system blockage
Air conditioning system blockage may occur where components have failed or pipework is damaged or kinked.
Ice formation can cause air conditioning system blockage.
Thermal expansion valve (TXV) failure or blocked orifice tube may cause abnormal air conditioning system pressures.
Air conditioning system electrical faults
Vehicle climate control systems can have complex wiring and electronic control which may require computer aided diagnosis to read or clear fault codes which may prevent air conditioning system operation.
A typical electronic climate control system may monitor external ambient and internal cabin vent temperatures,
refrigerant pressure and flow, also monitoring and controlling compressor engagement, rotational speed and operation of blower fans.
Refrigerant loss may cause a climate control module to log fault codes and prevent aircon compressor clutch operation.
FGAS Qualifications, Licencing & FGAS Legislation
Persons recovering refrigerant have a legal requirement to be F-gas trained and qualified as a refrigerant handler
to meet the requirements of 2015 EC regulations.
Companies recovering Refrigerants should also be FGAS company registered.
More about FGAS can be found here (link)
Refrigerants
Vehicle manufacturers have used a variety of refrigerants in vehicle mobile
air conditioning (MAC) applications.
Refrigerant at low temperature and pressure is cold so absorbs heat from the evaporator.
Refrigerant in the condenser is at high temperature and pressure so heat is rejected to the condenser.
Different refrigerant types and systems requiring a variety of dedicated service equipment.
Refrigerants are compared by Global Warming Potential (GWP).
Refrigerant R134a
R134a refrigerant (GWP1430) is a commonly used refrigerant utilised in pre-2017 vehicle
air conditioning systems and fleet transport refrigeration units.
Prior to vehicle aircon system repair involving disassembly of the refrigeration circuit any existing R134a refrigerant
must be recovered by FGas certified persons only.
Moisture and the Air conditioning system
Moisture causes problems with air conditioning system components because;
A dessicant pack within the vehicle receiver dryer aids moisture removal. Periodic renewal of the receiver dryer may be required.
After refrigerant recovery, a vacuum pump is used to evacuate the air conditioning system as part of servicing procedure boils off much accumulated moisture.
Recharging of the Air Conditioning System : Refrigerant Regas
Refrigerant recharge involves recovery of any remaining refrigerant from the air conditioning system by trained and qualified personnel to minimise environmental damage before any air conditioning system service maintenance work is undertaken.
Air Conditioning Refrigerant leak detection methods
Refrigerant leak detection methods include:
Vacuum test of Air Conditioning System
After refrigerant recovery, the air conditioning system is placed under vacuum to remove air and moisture. During a vacuum hold test the system is locked off whilst under vacuum and monitored for a time period to see if vacuum is lost indicating an air leak nto the system, or potential refrigerant leak. Most automatic refrigerant recovery machines used in garages use this method of leak test before refrigerant recharge is allowed. Refrigerant leaks may not show when the air conditioner system is under vacuum but only show by pressure test.
Oxygen Free Nitrogen Pressure Test
After refrigerant recovery, the air conditioning system may be pressurised with Nitrogen gas.
The air conditioner system is locked off whilst under pressure then monitored for gas pressure loss over a time period.
Loss of pressure indicates a leak.
Electronic refrigerant sniffer
An electronic device sensitive to air conditioning refrigerant is used to sense leakage by passing over aircon system components such as compressor, heat exchangers , pipework , and air vents.
Ultraviolet (UV) Dye
Addition of a quantity of UV dye into the vehicle air conditioning system can aid leak detection.
Should a refrigerant leak occur, the UV dye will glow when under UV light.
Component Access
Restricted component access can make leak detection on vehicle air conditioning systems difficult and complex to repair.
The only effective cure for a refrigerant leak is a repair or component renewal.
Refrigerant Pipes Hoses Repairs
Flexible Rubber Air Conditioning Hose
Rubber vehicle refrigerant hoses can become damaged by chaffing or rubbing leading to refrigerant loss.
Type SAE J2064 Air Conditioning Flexible refrigerant hoses for R134a may be manufacturer specific , or in some cases may be made up or repaired using fittings eg Hella beadlock
Copper - Aluminium Pipework
Aluminium refrigerant pipelines may be joined or repaired using specialist connector splices and couplers eg Vulcan Lokring, or by welding process.
Copper refrigerant pipelines may be made up using specialist equipment or joined using couplers or brazing process.
Following any hose or pipeline repairs a pressure test is recommended.
Refrigerated Insulated Vehicle Bodies
Insulated vehicle bodies are used to retain controlled temperature during transport of fresh and chilled products.
Some of our customers operate temperature controlled chiller vans for distribution and delivery of fresh goods.
Heat Pump function
Some air conditioning systems can reverse the flow of refrigerant to provide heating as well as cooling.
Vehicle Air Conditioning Mobile Service Areas:
Shropshire
Shrewsbury - Bayston Hill - Baschurch - Middletown - Oswestry - Wem - Whitchurch - Telford and Wrekin - Shifnal - Market Drayton - Newport - - Much Wenlock - Craven Arms - Ludlow - Ellesmere
Mid Wales
Welshpool- NewtownWe welcome enquiries.
Useful links :
Component Supply
Car Air Conditioning
Van air conditioning
Motorhome Air Conditioning
Truck Air conditioning
Bus Air Conditioning
Tractor Air conditioning
Excavator Air conditioning