What Causes the Car Air Conditioner to Alternate Between Hot and Cold?

2 Answers
McSilas
07/24/25 5:10pm
Introduction to the reasons why a car air conditioner alternates between hot and cold: 1. Damaged compressor capacitor: For the air conditioner to function properly, both the internal and external units need to work together. If the car air conditioner exhibits alternating hot and cold air, check if the external unit's compressor start capacitor is damaged. If so, it needs to be replaced. 2. Dirty filter: If the air conditioner hasn't been cleaned for a long time, it can also cause the air conditioner to alternate between hot and cold. A dirty filter or evaporator can easily lead to poor ventilation and heat dissipation, causing the compressor to overheat and shut down. Therefore, regular cleaning is necessary to maintain cleanliness. 3. Insufficient refrigerant: The air conditioner requires an adequate amount of refrigerant, commonly known as Freon, to cool. If the temperature inside the car alternates between hot and cold, check if the refrigerant in the air conditioning system is insufficient. If so, use other methods to address the issue. 4. Moisture in the air conditioning system: When high-temperature, high-pressure liquid passes through the expansion valve, all the liquid undergoes a rapid change, turning into low-temperature, low-pressure liquid. This low-temperature, low-pressure liquid causes the temperature of the evaporator to drop rapidly, so the air blown by the air conditioner motor becomes cold after passing through the evaporator.
Was this review help?
7
0
Share
VanJanelle
08/11/25 9:30am
Last month, my car's air conditioning was acting up—sometimes freezing cold like a fridge, other times unbearably hot, which was really annoying. I took it to the repair shop that day, and the mechanic checked the refrigerant, finding a leak that caused unstable pressure in the system, making the AC work intermittently. He also mentioned the compressor might have some issues, and if the pressure was insufficient, the fan speed would fluctuate. I usually make sure to replace the air filter regularly, and it wasn’t dirty, but this inspection revealed a small crack in the piping, possibly due to rough road conditions and bumps. I’d advise everyone not to delay—get it checked by a professional ASAP to avoid distractions and accidents on the road. Driving in summer without AC is unbearable, and spending a little to fix it saves a lot of hassle.
Was this review help?
16
4
Share
Expand All
More Forum Discussions

Where is the flasher relay located on the Baojun 730?

The flasher relay of the Baojun 730 is located in the control cabinet or control box. You can identify the actual component by referring to the following characteristics of relays. Introduction to relays: As an electrical control device, a relay is connected in a circuit to form two control systems: the control system (also known as the input circuit) and the controlled system (also known as the output circuit). You can trace the circuit to locate it. Generally, a relay has several main contacts plus two coil contacts, resembling a contactor. The main contacts are connected to the controlled system, while the coil contacts are connected to the control system. However, the contacts of a relay are usually visible, so you should be able to identify it based on this feature. Working principle of relays: When a certain voltage or current is applied to both ends of the electromagnetic relay coil, the magnetic flux generated by the coil passes through the magnetic circuit composed of the iron core, yoke, armature, and working air gap. Under the action of the magnetic field, the armature is attracted to the pole face of the iron core, thereby pushing the normally closed contacts to open and the normally open contacts to close. When the voltage or current at both ends of the coil falls below a certain value, and the mechanical reaction force exceeds the electromagnetic attraction force, the armature returns to its initial state, causing the normally open contacts to open and the normally closed contacts to close.
13
0
Share

How Many Years Until a New Car is Mandatorily Scrapped?

Currently, there is no mandatory scrapping period for new cars as long as they are private passenger vehicles. Service life for various types of motor vehicles: Small and mini taxi passenger vehicles have a service life of 8 years, medium-sized taxi passenger vehicles 10 years, and large taxi passenger vehicles 12 years; rental passenger vehicles 15 years; small training passenger vehicles 10 years, medium-sized training passenger vehicles 12 years, and large training passenger vehicles 15 years; public transport passenger vehicles 13 years; other small and mini commercial passenger vehicles 10 years, large and medium-sized commercial passenger vehicles 15 years; dedicated school buses 15 years; large and medium-sized non-commercial passenger vehicles, excluding large cars, 20 years; three-wheeled vehicles and low-speed trucks with single-cylinder engines 9 years, other trucks including semi-trailer tractors and full-trailer tractors 15 years. Vehicle scrapping standards: Reaching the prescribed service life; failing to meet the national standards for in-use vehicle safety technical requirements; atmospheric pollutants or noise still not meeting the national standards for in-use vehicle requirements; failing to obtain the motor vehicle inspection qualification mark within three inspection cycles.
10
4
Share

Can running a red light be handled in a different location?

According to Article 5 of the "Procedures for Handling Road Traffic Violations", running a red light can be handled in a different location. For red light violations recorded by traffic monitoring technology, the traffic management departments of public security organs at the place where the violation occurred, was discovered, or where the motor vehicle is registered all have jurisdiction. However, if the violator or the owner/manager of the motor vehicle disputes the facts of the violation recorded by traffic monitoring technology, they cannot raise objections in a different location. Methods to avoid running red lights while driving: When there are arrow signal lights, observe the arrow lights; otherwise, observe the circular lights. When the red light is on, the front of the vehicle must not cross the stop line. When the yellow light is on, the front of the vehicle must not cross the stop line. When the green light just starts flashing, if you are close and moving fast, you should proceed, as stopping might be impossible and you could cross the stop line. If you are far away, moving slowly, or the intersection is congested, you should stop. When driving in the city, develop the habit of looking for traffic lights whenever you see a crosswalk or stop line at an intersection.
18
5
Share

What is the fuel tank capacity of the Vela?

The fuel tank capacity of the Vela is 45 liters. The FAW Vela is based on the North American version of the ECHO. Standard fuel tank capacity for cars: Typically, small cars have a fuel tank capacity of 35-45 liters, while mid-size cars have a capacity of around 55-75 liters. A full tank usually allows for a driving range of approximately 500 kilometers. The size of the fuel tank is designed according to the vehicle's displacement and fuel consumption—larger engines with higher fuel consumption have bigger tanks, and vice versa. Generally, a full tank is designed to last for 400-600 kilometers. Lighter vehicles with smaller displacements tend to have smaller fuel tanks, whereas heavier vehicles with larger displacements naturally have larger tanks. However, most vehicles with a full tank can travel between 400-600 kilometers, with the exception of some off-road vehicles. How to check the fuel tank capacity: Nowadays, the fuel tank capacity is primarily checked by reading the fuel gauge inside the car. If there are no issues, the fuel gauge will accurately display the remaining fuel. The fuel gauge typically has 5-6 segments, each representing a portion of the remaining fuel in the tank. It is advisable to refuel when the gauge shows only two segments left to avoid running out of fuel while driving.
1
2
Share

What is the size ranking of Volkswagen SUVs?

Volkswagen SUV size ranking is as follows: Compact SUVs: Length ≤3900mm, representative models include Fiat Panda, Riich X1, Great Wall Mini SUV. Subcompact SUVs: Length ≥3900mm, ≤4200mm, representative models include Zotye 2008, Zotye 5008. Midsize SUVs: Length ≥4200mm, ≤4500mm, representative models include Honda CRV, Toyota RAV4, Nissan X-Trail, Hyundai Tucson, Hyundai ix35, Kia Sportage, Volkswagen Tiguan, JAC Refine, Chery Tiggo, Haima S7. Mid-size SUVs: Length ≥4500mm, ≤5000mm, representative models include Jeep Grand Cherokee, Volkswagen Touareg, Cadillac SRX, Acura MDX, BMW X5, Mercedes-Benz GLK, Porsche Cayenne, Dodge Journey, Infiniti EX35, BYD S6, Great Wall Haval H3, H5, Volvo XC60, Volvo XC90. Full-size SUVs: Length ≥5000mm, representative models include Buick Enclave, Cadillac Escalade, Land Rover Range Rover, Audi Q7, Infiniti QX56, Lincoln Navigator.
15
1
Share

Why doesn't the automatic transmission car move when shifting to R gear without stepping on the accelerator?

Automatic transmission cars not moving when shifting to R gear without stepping on the accelerator may be due to rusted brake discs or dirty transmission fluid. Rusted brake discs: If the brake discs are slightly rusted, it increases the resistance of the wheels. Polishing the brake discs can solve this issue. Dirty transmission fluid: If the transmission fluid is dirty or the clutch is slipping, it can cause this situation, and the transmission fluid needs to be replaced. Brake disc replacement cycle: Inspect the front brake discs every 60,000 kilometers and the rear brake discs every 120,000 kilometers. The maintenance cycles specified by different car manufacturers may vary, so the specific replacement cycle should follow the manufacturer's requirements. Transmission fluid replacement cycle: Under normal usage, for manual transmission vehicles, it is recommended to replace the transmission fluid every 3 years or 60,000 to 80,000 kilometers. For automatic transmission models, the transmission fluid should be replaced every 2 years or 40,000 to 60,000 kilometers. If the transmission has undergone repairs, especially major repairs, it is strongly advised to replace the transmission fluid every year or after driving 20,000 kilometers.
17
3
Share
Cookie
Cookie Settings
© 2025 Servanan International Pte. Ltd.