AUTOELECTRICS MOBILE PRODUCT SERVICES
Telford Shropshire UK 01952
407707

Vehicle Heating & Climate

INDEX
Online Shop
Auto Electrical Installation
Products & Services
Vehicle Battery
Starter Motors
Alternators
Onboard Power
Engine Tuning
Diagnostics
Vehicle Security
Towing & Towbar Electrics
Vehicle Wiring
Vehicle Heating & Climate
Diesel Engine Service
Fuel Injectors
Common Rail Diesel Diagnostics
Inspection
Vehicle Mechanical
Engine Cooling
Cam timing belt
Local breakdown service
Repairs list
Breakdown Assistance
Winter Motoring
Useful links
Vehicle Technology
Automotive Book Store powered by Amazon
Safety Policy
Contact Us
Product OffersImage: Heater hose Workshop pack of 1/2" Heater (coolant) hose
£28.05 + Vat for  20 metre roll
Air Conditioning & Cab Heater Diagnosis

heaterarray.jpg

We have specialised equipment to diagnose faults with cab night heaters as
together with a range of repair parts in stock.

Breakdown service to Telford & Shrewsbury, Shropshire areas.

Enquire for further details

enquiry form

Mobile Service for Car, Van, Truck Auto Electrics Telford Shropshire.
Telephone 01952 407707 www.autoelectrics.net emailer.jpg

Supply of heater fan motors, and air conditioning compressors, switches & components, heaters, repairs to Vans Trucks Minibuses Coaches Construction & Quarry plant and Agri machinery

The climate control system fitted to a vehicle has various functions:
 
  • Enhance driver and passenger safety by maintaining a comfortable   temperature
  • Enhance vision by keeping the windscreen demisted
  • Filter the air entering the passenger compartment  cabin to remove dusts and pollution
  • Drying of the air circulating in  the passenger compartment
  • Enhancement of vehicle security allowing windows to remain closed in hot weather

     
  • Our mobile repair service can come out to you to trace the fault with your car air conditioning system  or truck cab night heater if you are in the Telford or Shropshire areas.
    Tel :01952 247007
     

    Air conditioning systems operate on the principle of  heat transfer , and temperature change as  evaporation and condensation of refrigerant  gas, due to  a change in pressure occurs.

    New legislation applies to the servicing of Vehicle Mobile Air Conditioning Systems (MAC directive) of EC F-Gas (Fluorinated Gas) Regulations from 4th July 2010.

    see http://www.defra.gov.uk/environment/air-atmos/fgas/sectors/mobileaircon.htm for more details

     

    We can supply a range of the following Air Conditioning System Components including :
  • Air Conditioning Condensers and Evaporator Radiators
  • Automotive air conditioning condenser fans and evaporator blower motors
  • Contacts
  • Receiver filter dryers
  • Expansion Valves
  • Air Conditioner Compressors
  • Compressor Pulleys, Compressor component parts
  • Electromagnetic Clutches
  • Orifice Tubes
  • HNBR O-ring seal assortments
  • PAO (Polyolester) & PAG (Polyalkaline Glycol) Oils
  •  

    Air Conditioning service options:

  • Check refrigerant gas identification and charge status
  • Refrigerant Pressure Check at low pressure side and high pressure side test points of ac system to identify potential problem areas.
  • Electrical fault diagnostics using computerised diagnostic equipment via vehicle serial data port or with meter / oscilloscope test equipment.
  • Leak detection / UV dye injection or OFN Nitrogen pressure tightness (leakdown) test to identify air conditioning system gas leakage.
  • Regas and add recommended lubrication to system
  • Renew Pollen filter
  • Anti bacterial treatment of evaporator
  • Fault Diagnosis, Parts replacement and system repairs
  • Accredited Air Conditioning Technician  : Sub contract work for trade customers to comply with EC307/2008
  • Refrigerant and the Ozone layer : Climate change

    Refrigerant gas leak possibly damages  the ozone layer (search Montreal protocol and Kyoto protocol about climate change on Google) and there is strict legislation regarding recovery and recycling of refrigerant from vehicle airconditioning systems.

    Air Conditioning System Pressure Temperature Relationship of Refrigerant Gases:

    Vehicle air conditioning systems rely on change of temperature of refrigerant gas flowing through the fluid circuit of the air con system as the pressure of the refrigerant changes. As gas pressure increases ,temperature also increases and vice versa. 

    Basic vehicle air conditioner components and function

    Refrigerant
    The refrigerant is the fluid of the air conditioning system which transports heat.  The air conditioning system will not function without refrigerant. Most vehicle air conditioning systems use R134a as the refrigerant.
    A gradual loss of refrigerant gas can occur over time. The only effective cure for a refrigerant leak is a repair.

    Air conditioning systems which have lost the refrigerant gas charge will require leak testing with Nitrogen gas and repair before a new refrigerant gas charge can be undertaken. Persons handling refrigerant  must be qualified as a refrigerant handler and meet the requirements of EC307/2008 from 4th July 2010.

    Compressor
    The heart of the air conditioning system is the compressor which acts as a pump to move the flow of refrigerant around the system. Most vehicle air conditioning compressors are engine driven via the auxiliary drive belt and an electromagnetic clutch pulley. The compression of refrigerant gas causes an increase of gas pressure and temperature at the outlet of the compressor. The compressor can only compress gas. If liquid enters the compressor component damage will result.

    Air conditioning systems have a Low pressure side (suction side of compressor) and a High pressure side (output side of compressor). Manifold Pressure gauges can be attached to  service ports fitted to Low side and High side refrigerant circuit of the air conditioner system to aid  fault diagnosis.

    The lubrication oil (POE is recommended for R134a systems) for the air conditioning refrigerant compressor is injected in to the refrigerant circuit during service. A refrigerant leak may cause loss of this lubrication oil and eventually result in compressor damage.

    Condenser (high pressure side)

  • function : Transfer heat
  • from refrigerant.
    The Condenser is usually located near to the front of the vehicle just in front of the coolant radiator.
    High temperature ,high pressure refrigerant gas  changes state to refrigerant liquid by condensation as cooling air is blown across the radiator fins of the condenser by the radiator fans or condenser fan. Refrigerant flow direction is from top inlet as gas to bottom outlet as liquid. The Condenser is prone to stonechip and impact damage which may cause leaks.

    Suction accumulator
    A suction accumulator may be fitted at the evaporator outlet (compressor inlet side) to remove liquid from the refrigeration circuit to prevent compressor damage. Suction Accumulator devices are fitted to systems with orifice tube type metering devices.

    Receiver dryer:

  • function: To remove moisture and particle contamination (metallic particles,rust,silica gel, dirt and debris) from refrigerant circuit

  • A receiver dryer containing a desiccant gel pack to absorb moisture may be fitted after the compressor outlet (usually located between condenser and evaporator)  . Receiver filter dryers are fitted to systems with thermal expansion valve. During operation , moisture in the air conditioning circuit is removed by the filter dryer. Filter dryer units are a service item requiring periodic renewal as saturation occurs. Vehicle manufacturers recommend the receiver dryer is renewed every 2 to 3 years or 24000 miles or if the system has been opened to air for more than two hours (eg system dismantled). Standard vehicle aircon systems will have either a receiver dryer or an accumulator.

    Refrigerant passing around the air conditioner circuit flows through two heat exchangers , namely the evaporator radiator usually located behind the dashboard, and the condenser radiator located at the front of the engine bay in front of the coolant radiator. Transfer of heat occurs as air is blown through each heat exchanger radiator fins by fans.

    Metering device :

  • function to regulate flow of refrigerant

  • Depending on system type, either a thermal expansion valve or orifice tube restricts the quantity of liquid refrigerant entering the evaporator. This is the point where blockage can occur particularly if a compressor fails or ice build up occurs.

    Evaporator (low pressure side) :

  • function:
  • Transfer heat to refrigerant . Purify and dehumidify air.

    The pressurised liquid refrigerant passes via the metering device into the evaporator and changes state to a low pressure vapour.
    Air enters the vehicle cabin via a pollen filter which initially removes some dust particles . The air is then blown through the fins of the evaporator by the blower fan. Heat transfer occurs as heat is removed from the air as it passes  the evaporator fins  and out of the ventilation ducts providing a cool breeze inside the vehicle. Heat transfer occurs between the evaporator coils and the refrigerant causing the refrigerant to boil into a vapour as it flows away from the evaporator .
    The evaporator also acts as a dehumidifier and cleaner as moisture in the air which passes through the evaporator fins forms condensation on the external surface before exiting via drain tubes.  The evaporator can be a source of bad odours inside the vehicle of a build up of  contamination occurs

    Pressure Switches

  • High pressure switch acts to control condenser electrical fan and compressor electromagnetic clutch operation. Low pressure switch operates to prevent compressor operation in cases where a refrigerant leak may have occurred resulting in loss of system lubrication fluid which could cause compressor seizure.

    Moisture in the Ac system

    The main enemy of the air conditioning system components is moisture because;

  • Moisture can form ice and cause refrigerant circuit components to block.
  • Moisture within the refrigerant circuit can  mix with oil to form acids which corrode the air conditioner  system components.
  • Moisture accumulating on the surface of the evaporator and within air vents can breed bacteria causing smells inside the vehicle ( Sick car syndrome)

     Moisture can enter the refrigerant system if a leak occurs allowing air ingress or if the system has been opened.

    Removal of Moisture during air conditioning service

    Moisture is removed from the air conditioner system prior to adding refrigerant by using a vacuum pump to deep vacuum the air con system causing moisture to boil off as a vapour. Moisture is also absorbed by the PAO or PAG oil which should be drained and replenished. The filter dryer should also be renewed.

     

     

    Electrical fault diagnostics:

    If the blower motor has stopped working it may be as simple as a blown fuse or faulty switch, or could be more complex in a vehicle fitted with climate control and air conditioning.

    A typical climate controlled vehicle has a drivers control panel linked to a climate control computer with associated electrical circuits. The driver sets the desired temperature  , then the computer processes other inputs from various temperature sensors and pressure switches located in the cabin and engine compartments of the vehicle and provides outputs to control air vent flaps, blower motor speed, radiator fans, and switch the air conditioning compressor electromagnetic clutch on or off, enabling the preset temperature to be maintained.
    Even heat from the sun can affect the cabin temperature of the vehicle as it shines on the windscreens so a solar sensor may also be fitted.
    The extra load demand introduced as a vehicle air conditioning system operates means the vehicle will be fitted with a heavier duty alternator than standard to cope with extra power requirements.
    Climate control systems are often linked to engine control systems so idle speed is increased when the air conditioning is switched in, or when the vehicle is accelerating at wide open throttle (WOT) the air conditioning system compressor may be temporarily disengaged.

    Faults with computerised climate control systems may be diagnosed with the aid of electronic vehicle diagnostic equipment.

    Aftermarket equipment is available for most vehicles.
    Typical uses for stand alone heaters :
    Night heaters in trucks.
    Thermal comfort systems for ambulances, minibuses,coaches,marine craft,etc.
    Air conditioning units for retrofit on tractors and plant.
    Equipment such as crop sprayers may require additional carbon filtration to remove chemical from the atmosphere.

    Hot water handwash units are also available for fitment to service vehicles

    We are pleased to answer any enquiries.

    West Mercia Mechanical Services,
    10 Arrow Road,
    Telford.TF5 0LF.
    United Kingdom.
    Telephone: 01952 247007
    Mobile: 07703 558610

    autoelectricsnet.gif