The air conditioner in the car blows hot
Content
- Why is hot air coming out of the air conditioner into the car?
- How to determine why the air conditioner in the car is blowing hot air?
- F.A.Q.
- Why does the air conditioner produce warm air?
- Why does the air conditioner blow cold on one side and hot on the other?
- The air conditioner works on the move, but in a traffic jam it drives hot air. Why?
- Why does the air conditioner start blowing hot a few seconds after being turned on?
- The air conditioner blows hot - can the compressor overheat?
With the onset of the summer season, car owners often face a problem: the air conditioner does not cool the air to the desired temperature. Most often this is associated with compressor malfunctions, the drive of the air flow control damper of the interior ventilation system or with untimely maintenance of the air conditioning system.
Our article will help to find out why hot air is blowing from the air ducts instead of cold, as well as to detect and fix the breakdown.
Why is hot air coming out of the air conditioner into the car?
There are two basic reasons why the air conditioner in the car does not cool:
Diagram of the air conditioning system in a car, click to enlarge
- the air conditioner itself is faulty;
- Cooled air does not pass into the passenger compartment due to a faulty damper of the ventilation system.
in order to figure out why the air conditioner in the car blows warm, check is the compressor connected? when turned on. At the moment of connection, its clutch should make a click, and the compressor itself should start working with a characteristic quiet hum. The absence of these sounds clearly indicates clutch problem or the compressor itself. On vehicles with ICE less than 2,0 liters when the compressor is running turnover will increase and you will feel a decrease in power.
If the compressor turns on, but the air conditioner in the car blows warm air, check by touch the pipes through which the refrigerant moves. The tube (thicker) through which it enters the evaporator, leading to the salon should be cold, and going back - warm. In most models, when the air conditioner is turned on, the fan on the radiator immediately starts.
How to check an auto-air conditioner in 5 minutes: video
If the compressor is running, the temperature of the pipes is different, the radiator is blown by a fan, but the air conditioner in the car blows hot air - check damper operation and pay attention to the condition of the cabin filter. Change the climate settings, see if the temperature of the flow from the air ducts changes.
also keep an eye on the sound of the cabin fan when adjusting the air mixing. It should change slightly when the dampers move, as the nature of the movement of air flows changes. A soft click is also usually heard when the shutter is moved. The absence of these sounds indicates a jammed joint or servo failure.
All the reasons why the air conditioner in the car blows hot air are summarized in the table below.
The air conditioner blows hot air: causes of failure
| breaking | The cause of | Symptoms |
|---|---|---|
| Compressor or A/C fan fuse blown | Power surge | When the air conditioner is turned on, the compressor and fan do not turn on. If the problem is in the wiring, the compressor / fan, when powered directly from the battery, will start to work. |
| Short circuit in wiring | ||
| Jamming fan or clutch | ||
| Low refrigerant pressure in the system | Freon leakage due to depressurization of the circuit | Air conditioning errors in the on-board computer. The air conditioner pipes and its external radiator have a temperature close to the ambient temperature. If there is depressurization due to a crack in the leak area, there may be oil leaks and fogging on the tube. |
| Weak cooling of the condenser (outer radiator of the air conditioner) | The condenser is clogged with dirt from the outside | The radiator of the air conditioner (usually installed near the engine radiator) shows dirt, leaves and other vegetation, etc. |
| Failed condenser fan | The fan near the air conditioner radiator does not turn on, even if you turn on a large decrease in temperature (for example, from +30 to +15) on a stationary car. | |
| Clogged condenser passages | The air conditioner radiator has an uneven temperature to the touch. | |
| Compressor not connecting | Broken compressor pulley | The parts of the air conditioner (tubes, radiator) have approximately the same temperature, the characteristic sound of the compressor is not heard. Possible metallic noises, squeaking from the side of the pulley, although it itself rotates. |
| Stuck compressor | The belt that drives the compressor starts to squeak and whistle when the air conditioner is turned on. The compressor pulley spins when the climate system is turned off, but stops after it is turned on. | |
| Compressor clutch failed | The compressor pulley rotates freely when the motor is running, but the compressor itself is not running. When you try to turn on the air conditioning, you can not hear clicks and other characteristic sounds of connecting the clutch. | |
| Jamming of the heater damper (stove) | Breakage of the cable or breakage of traction | There is no reaction to a change in the position of the temperature controller. At a low outside air temperature, cool air comes out of the air ducts, after warming up the internal combustion engine it becomes warm, and then hot. |
| servo failure | ||
| A/C sensor failure | Mechanical damage to the sensor or wiring | Faulty sensors can be identified by computer diagnostics and other methods. Error codes P0530-P0534, in addition there may be branded codes from car manufacturers. |
| Broken belt | Belt wear | When the drive belt breaks (it is often common to attachments), the compressor does not spin. If the drive belt is shared with the alternator, there is no battery charging. On a car with power steering, the steering wheel becomes tight. |
| Air conditioning compressor wedge, generator or power steering | Same symptoms as above plus return of problem after belt change. With a weak tension, it is difficult for the starter to start the engine, the strap begins to whistle, and one of the attachment pulleys will be stationary. |
How to determine why the air conditioner in the car is blowing hot air?
Do-it-yourself machine air conditioner diagnostics: video
In order to determine the reasons why the climate control blows hot air, there are 7 basic air conditioner faults.
For a comprehensive diagnosis of a machine air conditioner, you need:
- autoscanner for computer diagnostics;
- UV flashlight or a special device that detects freon leakage;
- service kit with pressure gauges in order to determine the presence of freon in the system;
- multimeter;
- assistant.
Checking the fuses
First of all, you need to inspect the fuses responsible for the operation of the climate - the diagram on the cover of the fuse box will allow you to find the right ones. If the fuse blows immediately after replacement, this indicates a short circuit in the wiring or a jammed clutch or compressor.
Computer diagnostics and error reading
Deciphering error P0532 in the FORScan program, click to enlarge
To determine why the air conditioner is blowing hot, its error codes in the engine ECU will help, which can be read by an OBD-II scanner like Launch or ELM-327 and the corresponding software:
- P0530 - the pressure sensor in the refrigerant (freon) circuit is faulty;
- P0531 - incorrect readings of the pressure sensor, freon leakage is possible;
- P0532 - low pressure on the sensor, possible leakage of freon or problems with the sensor wiring;
- P0533 - high pressure indicator, possible damage to the sensor or its wiring;
- P0534 - Refrigerant leak detected.
Finding freon leaks
Finding freon leaks using UV radiation
Oil smudges and fogging of the pipes and their junctions help to localize the freon leak, since in addition to the refrigerant, there is a little oil in the circuit to lubricate the compressor.
For measuring freon pressure and recharging the system need special installation. The services of professionals will cost 1-5 thousand rubles, depending on the complexity of the repair, if any. For self-measuring pressure and refilling the refrigerant, you will need a service kit (about 5 thousand rubles) and a can of freon (about 1000 rubles for R134A freon).
Condenser test
The fan will not be able to cool the condenser clogged with debris
If there are no errors and freon leaks, but the air conditioner drives hot air, you need to inspect the condenser. Sometimes you need a pit or lift to access it, and in some cases you even need to remove the grille and / or front bumper.
If you have access, you can feel the condenser, which should warm up evenly. But, unfortunately, due to the proximity to the main radiator, normal tactile diagnostics is very difficult. It simply heats up from other nodes of the engine compartment, so it is possible to check the radiator qualitatively (for example, for clogging) only in the service.
Clogged with leaves, dust, insects and other debris, the condenser must be washed with a special detergent and a high pressure washer. this should be done with caution, in order not to jam the lamellas. To do this, reduce the pressure and place the sprayer no closer than 30 cm from the surface.
Checking the compressor drive
Visual inspection of the drive belt and compressor pulley
Inspect the drive belt (often also turns the alternator and power steering) for integrity. If the belt is loose or frayed, in addition to the air conditioner, there will be problems with the above nodes.
Before replacing the belt, check the rotation of all pulleys. Turn the generator, power steering, air conditioning compressor by hand to make sure that one of these parts is not jammed. To test the compressor itself, you will have to apply 12 volts to its clutch forcibly or try to turn on the air conditioner when the car is running on battery without a belt.
Compressor Diagnostics
If the diagnostics according to the previous points did not reveal any problems, but the air conditioner does not cool, it works like a fan and blows warm, check if its compressor is working. Ask an assistant to sit in the passenger compartment and, on command, press the AC button, while you yourself open the hood and listen to the compressor.
Do-it-yourself machine compressor diagnostics: video
When the air conditioner is turned on, the compressor should start to work, this is indicated by clutch connection sound and characteristic pump noise. Whistling, noise and immobility of the compressor pulley are a sign of his jamming.
When nothing happens when the assistant turns on the air conditioning, this indicates problems with the drive (solenoid, actuator) of the clutch or with its wiring. A multimeter will help distinguish the first from the second. Turning on the tester to measure direct current (DC range up to 20 V for models without auto-detection), you need to remove the chip from the coupling and connect the probes to the lead wires (usually there are only 2 of them). If, after turning on the air conditioner, 12 volts appear on them, the problem is in the clutch itselfif there is no voltage, her posting.
If there are problems in the wiring of the clutch, you can eliminate other breakdowns by turning on the air conditioner and connecting it directly to the battery (preferably through a 10 A fuse). In the absence of other faults the compressor should run.
Fan check
When you turn on the air conditioner with the car stationary, the radiator fan should turn on. The situation when, when the air conditioner is turned on, warm air blows in the parking lot and slow driving, and it becomes cool on the highway, it usually appears precisely due to lack of forced airflow. The serviceability of the fan and wiring is checked in the same way as the couplings, using a tester and direct connection to the battery.
Checking the dampers of the climate system
Air conditioning damper drive in a Volkswagen Passat
In a situation where cold air is not blowing from the air conditioner to the car, and all previous checks have not revealed anything, there is a high probability of problems with the operation of the dampers that regulate air flows in the climate system.
In most modern models, there is no radiator valve for the interior heater, so it always heats up. When the damper responsible for the insulation of the stove is jammed, warm air flows from the air ducts into the car when the air conditioner is running.
In modern climate controls, dampers and regulators are made in the form of servo drives. Diagnostics can be done using specialized programs, but to check the dampers and their actuators, partial disassembly of the air ducts, and sometimes the front panel of the car, is required.
Diagnosis by pressure in the air conditioning system
If you have a service kit for diagnosing car air conditioners, you can look for the causes of hot air from the air ducts according to instrument readings. The combination of features is shown in the table below.
Auxiliary circuit for determining the pressure in the system using pressure gauges
Diagnostics of the air conditioner in a car by pressure and temperature in the system
| Pressure in the circuit L (low pressure) | Pressure in circuit H (high pressure) | Tube temperature | Possible breakage |
|---|---|---|---|
| poor | poor | Warm | Low Freon |
| high | high | Warm | Coolant recharge |
| high | high | Cool | Recharging or airing the circuit |
| Normal | Normal | Warm | Moisture in the system |
| poor | poor | Warm | Stuck expansion valve |
| Clogged condensate drain pipe | |||
| Clogged or pinched high pressure circuit H | |||
| high | poor | Warm | Compressor or control valve defective |
F.A.Q.
Why does the air conditioner produce warm air?
Main causes: refrigerant leak, condenser fan failure, damper wedge, compressor or clutch failure. Only a deep diagnosis will help to accurately determine the cause.
Why does the air conditioner blow cold on one side and hot on the other?
In most cases, such a symptom indicates the incorrect operation of the dampers of the ventilation system that distributes air flows.
The air conditioner works on the move, but in a traffic jam it drives hot air. Why?
When the air conditioner blows either cold or warm, depending on the speed of movement, the problem is usually in the condenser (air conditioner radiator) or its fan. At low speed and when parked, it does not remove excess heat, but at speed it effectively cools the air flow, so the problem disappears.
Why does the air conditioner start blowing hot a few seconds after being turned on?
If the air conditioner blows hot only immediately after turning it on, this is normal, it also did not enter the operating mode. But if this process continues for more than 1 minute, this indicates a low pressure in the circuit due to a lack of freon, inefficient operation of the compressor or condenser.
The air conditioner blows hot - can the compressor overheat?
If there is not enough refrigerant in the system, the compressor will overheat. At the same time, its wear accelerates, the pressure created decreases over time, and the problem of inefficient operation of the air conditioning system is exacerbated.
