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Questions tagged [hvac]

HVAC - Heating, Ventilation, Air Conditioning.

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16 votes
5 answers
78k views

When car is standing still, I smell Diesel exhaust. Why?

In my 2003 Opel Vectra, the cabin air smells of Diesel exhaust while stopped at e.g. a red light. The exhaust smell goes away when driving, and it also doesn't come back if I turn the ventilation off ...
Torben Gundtofte-Bruun's user avatar
13 votes
2 answers
47k views

Is it okay or useful to run heat and AC at the same time?

Most cars that I've seen in my life have a heat slider or dial, which goes from coldest to hottest, and also a button or switch that is labelled "AC". When the heat dial is set to cold, turning on the ...
snetch's user avatar
  • 233
12 votes
7 answers
46k views

Can a car AC unit be run on just the car battery?

This might be a silly question but I was wondering if a car AC unit be run off entirely on battery or alternator? As this could help in Preventing power loss during important times such as ...
saurabh64's user avatar
  • 1,072
9 votes
3 answers
1k views

Are A/C Control Panels Universal?

Are A/C Control Panels (the panel that controls the: Fan Speed, Temperature, and Head/Foot air flow direction) in cars are universal, similar to USB connections are for computers? For example, I would ...
Munstr's user avatar
  • 91
9 votes
2 answers
26k views

My vents randomly switch between face / windshield... how do I fix this?

I have a 1998 Ford Windstar (more details on demand if necessary.) I rarely use any vent setting besides "face", and I try to avoid using AC because my gas mileage is already lousy. About two months ...
MT_Head's user avatar
  • 1,122
9 votes
3 answers
7k views

how can I quiet a 'chirping' ventilation fan motor blade?

I have a 2006 VW Golf and the internal fan motor that blows the a/c & heat will start to 'chirp' (sound something like a bird singing) randomly. I believe the fan blade needs to be lubricated, ...
Patrick's user avatar
  • 2,630
8 votes
2 answers
4k views

Vehicle AC works initially, but after driving for a while (hour+), the airflow drops to the point being ineffective

I have a 2004 Ford Excursion with the 6.0 powerstroke. Most the time, the AC works fine, but after a long drive in hot weather, the front AC barely blows out of the vents. The rear works fine, in fact,...
Alex Estrada's user avatar
8 votes
3 answers
748 views

What can I do to prevent my air conditioner from smelling moldy as the temperatures begin to rise?

What can I do to prevent my air conditioner from smelling moldy as the temperatures begin to rise? Every year someone I know or myself begins to get an odor from their air conditioner that's musty or ...
DucatiKiller's user avatar
  • 32.9k
8 votes
1 answer
24k views

My AC works well at night only

I'm unhappy with the performance of my '04 Pontiac GTO's AC. Here are the symptoms: Cooling goes down to zero when the car is stationary, starts to cool after the car has been moving for some time ...
Zaid's user avatar
  • 39.2k
8 votes
1 answer
4k views

How to get items out of the HVAC system from a 2003-2007 Honda Accord

Before I ruin my dashboard/car, I wanted to know if my approach is correct. I don't know much about cars but logically, it seems like a simple enough task to remove vents, reach in and grab items, ...
Classified's user avatar
7 votes
3 answers
8k views

What's the quickest way to defog a windshield?

For a properly functioning auto, what's the quickest way to defog the windshield? There are lots of air control options - hot vs. cold air, exterior vs. recirculated air - but which are the most ...
KatieK's user avatar
  • 249
7 votes
1 answer
1k views

Measuring A/C refrigerant I got 96 PSI, is 96 PSI bad?

I bought a car refrigerant gauge online because my A/C is not cooling the air at all and the first suggestion was to check your refrigerant to see if it is empty or low. I found out where my car's "...
syn1kk's user avatar
  • 416
6 votes
2 answers
18k views

Why might lower settings of a dashboard fan not work if the highest does?

My wife bought a Nissan Note second hand and the internal ventilation fan works on the highest setting (3 or 4) but not on the lower settings. We've checked the fuses and all seems fine there. Could ...
Bernhard Hofmann's user avatar
6 votes
1 answer
739 views

How do final stage resistors fail?

I replaced the FSU on my BMW today to restore normal fan speeds to my HVAC blower (having just 20% fan speed in 40+ °C isn't always comfortable). After removing the old resistor pack, curiosity got ...
Zaid's user avatar
  • 39.2k
6 votes
2 answers
2k views

Which knob setting best cooks the mold inside HVAC?

I am trying to eliminate odors inside HVAC by cooking the mold that is presumably causing them, as suggested in https://mechanics.stackexchange.com/a/146/15334 (which got 39 upvotes) However, I don't ...
MWB's user avatar
  • 215
6 votes
2 answers
36k views

Water dripping on driver's foot. How to fix it?

Just this morning I noticed there is a water dripping into my shoes while driving. My aircon is open. The weather is sunny and warm. My car is Toyota Vios.
H3n's user avatar
  • 91
6 votes
1 answer
22k views

How does clogging tailpipes result in carbon monoxide in the cabin?

Reports like this of people dying from CO poisoning in idling cars due to "clogged tailpipes" are disturbingly frequent. But how can this happen if the car is outdoors? First of all, how does a ...
feetwet's user avatar
  • 1,199
6 votes
2 answers
127 views

1986 VW Westfalia van A/C

I had my AC refrigerant professionally changed to Red Tek in my van. It worked well for 2 or 3 years but then stopped cooling. I successfully refilled with difficulty and it was fine for a further ...
Jack Whitlie's user avatar
6 votes
1 answer
1k views

Vauxhall Vectra C Blower Motor Sqealing / Clunking

I have just replaced my Blower Motor Resistor as my fan wouldn't work on any setting other than 4 (in line with a previous post: How to troubleshoot a fan that won't work unless it's on it'...
webnoob's user avatar
  • 241
6 votes
1 answer
20k views

Hot air only flows to vents, not to defrost?

I have a 1995 VW Jetta GL, 2.0 engine, 5 speed, a/c. My heater won't switch between defrost, floor heat or vents. It's stuck on the vents and I can't seem to find out why. I have torn apart the ...
PATRICK's user avatar
  • 61
6 votes
2 answers
4k views

Foul Smell when turning on air conditioning

I have a 2007 Chrysler Aspen, and recently (past 2 weeks) when I turn on the ac, I notice a 'foul' smell, like burnt rubber, or even sulphur-like. The smell will last a few minutes and will gradually ...
Delia's user avatar
  • 61
6 votes
1 answer
323 views

Why does the air conditioning suddenly blow cold air?

I have a BMW 320i 2008. When I turn on the hot air and Automatic recycle, after a point, it blows cold air for 5-10 mins, then back to hot and so on. This doesn't occur when I put the recycle on. Any ...
dqm's user avatar
  • 161
5 votes
3 answers
2k views

How do race drivers clear foggy windscreens?

I know that, in order to decrease weight, race cars may remove AC and heating systems as these are not essential. However, when driving, if their windows get foggy due to cold weather, how do they ...
James Wilson's user avatar
  • 2,756
5 votes
3 answers
6k views

Defogger won't work in 2008 Chrysler 300

As winter is now here a functional defogger is a requirement yet this year my car won't defog no matter what I try. All vents in the car are functional and blow whatever is pumped through them (eg I ...
scunliffe's user avatar
  • 151
5 votes
5 answers
2k views

Why is there no vent option for combined defrost/face?

I've wondered about this one question for the better part of twenty years: why is there no option for you to set the air vent to split between face and defrost? That is, the airflow options on (...
Angermonsoon's user avatar
5 votes
4 answers
17k views

How to clean Car's HVAC and AC system

There is a relatively unpleasant smell in my car's HVAC, AC or heating system. Failed idea#1: I removed the cabin air filter and sprayed lots of Lysol in there. It did not help much. Failed idea#2: ...
Allan Xu's user avatar
  • 950
5 votes
2 answers
14k views

Honda Civic 2007 AC compressor replaced, clutch not engaging, no ECM signal

I have a complex AC problem in my Civic. I need to tell you the story so that you might get a potential diagnosis of the issue: Car started having problems with AC in 2015. After driving for a while, ...
Joseph On Cars's user avatar
5 votes
2 answers
2k views

How can I determine my HVAC layout?

Answers to Why does my A/C blow foul smelling air when it first turns on? suggest several fixes that depend on knowing where in the car they are located. I can't determine in any of my cars where the ...
feetwet's user avatar
  • 1,199
5 votes
1 answer
3k views

How to troubleshoot a fan that won't work unless it's on it's on the highest setting?

My car fan won't work unless it's on 4 (full power). I have 4 options of power for the fan 1 - 4 but nothing happens on options 1 - 3. I have taken the panel off and cleaned all the contacts for the ...
webnoob's user avatar
  • 241
5 votes
1 answer
1k views

2012 Jeep Patriot Heater Core Leak

Purchased late 2012 new from dealer. My son reported "hot oily amber drips" on his bare rt. foot while driving home from the beach. I investigated and it very much appeared to be coolant leaking from ...
Jimmy Fix-it's user avatar
5 votes
1 answer
138 views

What's this strangely marked control on my Eclipse?

My 1995 Mitsubishi Eclipse, and presumably other Mitsubishis of the same era, has a control over by the rear windshield wiper control, near the center vents. It's got 2 pictures of a person sitting. ...
Brian Knoblauch's user avatar
5 votes
1 answer
3k views

What should I use to lubricate the flaps that controls the temperature and which vents the air comes out of?

The control shafts that move the flaps which control the the hot/cold air and which vents the air come out have broken. The car is a 1999 93 Saab so I'm assuming that the hinges (the flap has a peg ...
Alex's user avatar
  • 153
5 votes
3 answers
2k views

My Ford Focus 2009 has a lot of vibration when the A/C is off?

Most of the time cars vibrate when you turn the A/C on, but mine is the other way around, when the AC is off the car has a lot of vibration, if I turn on the A/C it will stop vibrating, I already went ...
isJustMe's user avatar
  • 101
5 votes
1 answer
8k views

toyota corolla 2001 air duct smell [duplicate]

My 2001 Toyota Corolla recently started smelling very foul whenever the air system was turned on. According to the research I've done online, there is no cabin air filter to change. The glove box ...
Rodney's user avatar
  • 53
5 votes
2 answers
680 views

Clunking noise from dash of 2005 Ford Explorer

All of a sudden there is a loud clunking noise coming from the dash of my 2005 Ford Explorer. Observations It definitely sounds cyclical. Exists only when climate control system is ON. Sound ...
reevesjb3's user avatar
5 votes
2 answers
11k views

2006 Jeep Liberty - AC clutch won't engage

The AC clutch on my Jeep Liberty 2006 won't engage. Here is what I have checked so far. Fuse 14 in the passenger cabin 21 in the engine compartment are ok AC relay ok When I jump the AC relay I ...
mark b's user avatar
  • 51
5 votes
0 answers
64 views

Saying its running hot but full of coolant and not over heating [closed]

2005 Hyundai Elantra. Says its running hot but has coolant and so far hasn't over heated and also can't turn on heat in car because smoke pours from vents into the inside of car.
Heather's user avatar
  • 51
4 votes
2 answers
1k views

Does putting down the visors help defogging the windshield?

My old Fiat Marea Weekend had instructions for defogging the windshield on the inside of the driver's visor: Turn the blower on max Turn the heat on max Turn the recirculation off Put down ...
SQB's user avatar
  • 786
4 votes
4 answers
36k views

What do I risk if I don't fix my leaking evaporator core on my 2004 Jeep GC?

The shop just tested my non-working AC, and recharged the freon - so, for now, it's working. Cost $118 all in. However, they tell me I have a leak in my evaporator core, and that it will take 16 ...
marfarma's user avatar
  • 265
4 votes
3 answers
59k views

Why does the radiator fan have to start when turning the A/C on?

The inner blower fan is the one that pushes the air and not the radiator fan.
ronenfe's user avatar
  • 285
4 votes
2 answers
2k views

AC stops blowing air after a period of time

After leaving the car off for a few hours, and starting it up, the AC always works 100%, the fans blow very nice cold air and it can last 20+ minutes. Sometimes it never stops working fully (yay) but ...
Enigma's user avatar
  • 141
4 votes
1 answer
4k views

Is it bad to immediately crank the air conditioning all the way up when you start your car on a really hot day?

There have been times in the summer when my car is in my driveway all day in 100-degree weather, and combined with the sun, it must be 140+ degrees in my car. Can it damage or shorten the life of my ...
Josh Withee's user avatar
4 votes
1 answer
129 views

Indica petrol 2006,coolant leakege

I have bought a 2006 petrol Indica Xeta,and changed the normal radiator water with valvoline super koolextra. After 50km of driving, I kept the vehicle in my car porch. After 5 days When I opened the ...
Girish kumar V T's user avatar
4 votes
2 answers
3k views

Subaru Blitzen overheating but heater blows cold air

I have a 2000 Blitzen. My heater blows cold air and tonight it overheated. It is not losing water. Would this be the thermostat or an air blockage?
sam's user avatar
  • 41
3 votes
5 answers
32k views

1999 Honda Accord can't change ventilation mode

My wife has a 1999 Honda Accord. The buttons that let you switch the ventilation between face/feet/defrost don't work. It is stuck on face so you can't defrost in the morning. The buttons for face, ...
Kevin's user avatar
  • 247
3 votes
2 answers
12k views

How do I flush out bad smells in my air conditioning? [duplicate]

My car seems to have a pretty bad smell in the air conditioning. WHat is the best way to flush out these smells?
yuritsuki's user avatar
  • 437
3 votes
2 answers
7k views

why condenser is placed before the radiator?

i am confused why radiator is placed after the condenser in an automobile. what will happen if we place radiator before the condenser? whether it is related to design or temperature.
roshan kumar's user avatar
3 votes
2 answers
3k views

2007 Pontiac g6 keeps blowing fuse

There's a fuse under my hood that controls the heat, ac, defroster etc. a couple months ago they all stopped working. I checked the fuse and alas it was blown. I've bought replacement fuses with the ...
munale's user avatar
  • 113
3 votes
3 answers
18k views

Does outside temperature sensor affect the HVAC system?

Car: 2010 Mazda 3 2.5L Manual My car's outside temperature display is way off. It is showing warmer than the actual temperature. For example: Today the real temperature was -9C and it showed +18C. ...
rana's user avatar
  • 602
3 votes
2 answers
2k views

Can I replace my AC Compressor myself? 2008 Vauxhall Astra 1.9

On my 2008 Vauxhall Astra 1.9 CDTI my AC Compressor has gone I was wondering how easy it is to replace myself? I'd get the system drained at a garage first. I've included the service instructions ...
George's user avatar
  • 6,545