Question about 1995 Mercedes-Benz C-Class

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How do I tell if my 1999 C280 is out of R134 or that is might be a relay switch or "other" isssue. Fan and motor run fine but blows just hot air.

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Have the system tested,the only way to know for sure what the problem is.

Posted on Jul 16, 2009


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My 2010 Chevrolet Aveo LT is making a clicking sound when I turn on my AC, but I turn it off it stops- occassionally blowing cool air but then turning hot. Any suggestion for an easy fix without breaking...

Your system is low on R134....the clicking is the compressor engaging and disengaging. You will get cool air while compressor is on, then warm when its off. They will act this way when R134 is low. Now either a leak in the system, or the system just needs a boost. Another thing to check is the condensor fan under the hood.When you turn the AC on,the condensor fan needs to be running, if its not then its a bad fan motor,relay, or fan sensor. I don;t know what your abilities are, but maybe armed with this info you can work on it yourself, or at least not get taken advantage of at the mechanics. Good luck !!

May 26, 2014 | 2010 Chevrolet Aveo 1.6

1 Answer

Relay switch for fans on 99 dodge caravan keeps blowing causine engine to over heat ng

If the relay is getting too hot, the most common problem is a faulty radiator fan. The fan motor pulls current thru the relay. The radiator fan motor may be failing after it runs for a period of time.

Jul 05, 2013 | 1999 Dodge Caravan

1 Answer

Air conditioner works fine while driving. When stopped for a light, temperature gage goes up and fan blows hot air.

Hello: Check the radiator cooling fan. With engine running and A/C on open hood look down on the back-side of the grill, that's where the cooling fan is. It should be running, if not check the fuses, cooling fan relays/module if they are ok then you may have a cooling fan motor failure. You can use jumper cables to hot wire the fan motor to see if it runs.

Sep 14, 2011 | 2002 Saturn Sl

1 Answer

Air conditioning starts to blow cold, then it blows hot, turn blower motor switch off and on and then it will start to blow cold all over again and then blows hot air. they replaced the orfix and...

Sounds like the secondary engine / A/C cooling fan is not running.... Fine on highway is due to more airflow across the condenser...

Electric Fan(s) not working, Checking the fan(s), relay, fuse and engine temperature sensor's.
Verify that the fans work by unplugging them and run jumper wires to the fan(s) from the battery. If they run, your problem lies elsewhere. If either does not run, it's the motor.
Next thing to check is for power at the fan connectors. You have to be cautious doing this because the engine needs to be running and warm if not almost hot, and the A/C also needs to be on. (Both must be on and running for the duration of this checklist.) The A/C fan is on the passenger side and should come on almost the instant the A/C is turned on. It is also the secondary engine cooling fan and should cycle on and off in relation to engine temperature. Use a test light to probe the two wires on each fan. If you find power the fan motor(s) is/are probably bad. If there is no power to fans, roll up your sleeves!

You didn't mention the year or model so this will be generic. The temperature switch is usually located above the oil filter. If the dash gage is working, its probably OK. Next is the Fan Control Temperature Sensor, located IN or CLOSE to the thermostat housing. You will find out if it is working later is this checklist. I just wanted you to know where it is. Next is the relays and fuse's. Usually located in the engine compartment on the passenger side power distribution box. You will need to remove anything over the cover to open it. If the fuses are OK, tap on the relays or pull them out and push back in. If the fans are still not running, pull a relay and probe the socket terminals for power. Two of the terminals should have power, usually criss-cross from each other. One hot terminal is battery power, and the other is the "signal" voltage which triggers the relay to send 12V battery power to the fan. This signal voltage comes from the sensor at the thermostat. If only one terminal has power, then I would replace the thermostat sensor if not both.

Aug 20, 2011 | Chevrolet HHR Cars & Trucks

1 Answer

Hi I have purchased a 1999 Dodge Ram 3500 van and the motor run fine, but when I turn on the a/c, the motor acts sluggish and eventually cuts off. I noticed that there was a switch installed to the dash...

IT sounds like someone has installed a manual fan switch in you truck. This was done either because the fan relays were faulty or because of a wiring issue. The reason behind the poor performance is likely to be several different things. But in order to check this out thoroughly you should have the engine codes read first. This can be performed at you auto parts store like Autozone or Oriellys. Once you have the engine diagnostic codes this will tell you if you have a faulty sensor. The other reasons for poor performance is due to the engine temp increasing from the A/C running and the Electric fans not cooling the motor. A hot engine will perform very poorly with a lack of power and hesitations. This is because the engine is so hot that the fuel being sprayed into the manifold is being partially burnt before it's used in the combustion chambers. Another cause is called vapor lock. When the fuel lines become so hot the fuel inside them actually turns from a solid into a vapor, when this happens you get a greatly reduced amount of fuel pressure which can cause the vehicle to die or stammer. Making sure that you have a properly cooled engine will help cure most of this. By the way, you should have that fan switch in the on position at all times if the real fan relay is not functioning.

Aug 03, 2010 | 1999 Dodge Ram

2 Answers

No air coming out of the vents

It sounds like the heater motor may not be operating. When you switch the heater fan on can you hear the motor running? If not then it may have blown the heater fan fuse, check the fuse's and then try it again. If the fuse is ok then it could be a faulty switch or fan motor.

Apr 02, 2010 | 2004 Chevrolet TrailBlazer

1 Answer

My 2003 Duango has a bad blower motor resistor, I think. The back fans blow fine but nothing in the front unless I kick the little box in the passenger side. Ordered a new one, but now the ac blows hot....

likely two different issues ... the clutch that allows the compresser to operate is controled by several things
1. if refrigerant (r134a) is low then the clutch will cycle or not come on at all as the pressure in the system drops below a critical value .. in general if this is the case it may work better (for longer) if it is really hot out .. and maybe not at all when its cool
2. the system detects the fact that the front blower is turned on before it will allow the compressor to operate .. could you have damaged the fan speed switch assembly or wire connectors while kicking or changing the resistor ???
3. the switch that detects low refrigerant pressure could be bad and that switch sometimes operates a relay that has a high failure rate in some car makes ..that would be called the compressor clutch relay, AC relay or some such ...the nature of this relay problem is that the clutch turns on and off randomly then eventually doesnt come on at all ..

if there is no damage to the blower switch or wiring then i would check the refrigerant pressure .. in r134 systems slow leaks are often seen that cause the pressure to drop to the point where the system cant make up its mind about running. typically the compressor will run for a few seconds at a time .. a steady but fast cycling (not random) you can get a r134 pressure gage at any auto parts shop but you should know how to use it or find someone that does ..

Aug 17, 2009 | 2006 Hyundai Accent

1 Answer

Air and heat not blowing air through vents

Either Your fan switch is burned out or you blower motor is no good, your blower motor is on the passenger side under the dash. Before you replace any parts you need to check your fuses and relays under your hood and in the car. Usually if your fan switch goes bad you will still get some air blowing thru the vents, so my guess would be blower motor, If its not a blown fuse or relay.

May 28, 2009 | 1999 Cadillac DeVille

1 Answer

00 Mitshubishi Eclipse A/C blows out hot air.

fan clutch is not energizing, is it?

Apr 16, 2009 | 2007 Honda Odyssey

1 Answer

Blower on heater not working

i am no expert on this type of car but you can try this. first i would see if you got power from the switch. if you can get to them. if no power than i would say it is the switch. but also i would find out if there is a resister for the heater. if there is this could also be the problem. heater resisters chg. the speeds for the heater motor and also make heater motor run. its either located on the heater box or the air evaporator box if it has one.

Jan 06, 2009 | 1998 Mercedes-Benz C-Class

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