thejames Posted February 28, 2011 Report Share Posted February 28, 2011 My car seems to take an age to warm up - specifically I'm talking about the air con, not water temp. On a cold morning, it will take about 4-5miles/10-20mins to get any kind of warmth from the A/C. (Temp set to max 32) Strikes me as too long... I'm confident that all my previous cars warmed up quicker than that. Tomorrow I'm taking it to a local Independent who's going to service the A/C for me. I'm hoping that it's just low on gas on something. So... how long does your car take to heat up of a frosty morning? Thanks, James. Link to comment Share on other sites More sharing options...
momo Posted February 28, 2011 Report Share Posted February 28, 2011 You shouldn't really use the AC to warm the car up dude! Its best when cooling the cabin/dehumidifying etc.. On a cold morning I put both screen heaters on.. Takes approx 4-5mins to warm up fully. You've just reminded me - I need my AC charging too! Link to comment Share on other sites More sharing options...
thejames Posted February 28, 2011 Author Report Share Posted February 28, 2011 So you're saying AC's just for cooling..? Whenever I've used non-AC heaters before it actually fogs up the windows! Link to comment Share on other sites More sharing options...
scrimja Posted February 28, 2011 Report Share Posted February 28, 2011 Why wouldn't you be able to use A/C to warm the car up Fairly sure it says you can in the manual. The car let's me do it too, surely it'd stop me if it was unhealthy for it? I prefer A/C air to non A/C'd. Dunno why, just do lol. Link to comment Share on other sites More sharing options...
DJ Syxx Posted February 28, 2011 Report Share Posted February 28, 2011 Perfectly fine using A/C in winter. Worst thing you can do is not use it for long periods of time. Link to comment Share on other sites More sharing options...
mit Posted February 28, 2011 Report Share Posted February 28, 2011 You should be able to use AC to warm the car up as well. If yours is taking a long time to warm up then you probably need to have it looked at. AC should warm the car up faster than relying on the engine. There are also OBC options that will either start blowing air immediately or only increase it once the engine temperature is high enough to get the temperature you selected, so depending on your setting, your heater might not blow anything until the engine is hot enough to blow air at 32 degrees. I hardly ever use my AC, even in the summer, as my roof is usually down if it's warm enough to use AC Link to comment Share on other sites More sharing options...
Gaygle Posted February 28, 2011 Report Share Posted February 28, 2011 I heard that some cars have some kind of reverse valve which basically heats the air instead of cooling it. Don't think the E46 has this valve thingy though. That's why the airconditioners in your office can heat up as well as cool down. However, i don't use the A/C if i want to heat the car up, only if i want to demist the windows. The heater comes on hot after about 2-3 minutes of 60mph driving. Link to comment Share on other sites More sharing options...
momo Posted February 28, 2011 Report Share Posted February 28, 2011 Whoops! Sorry - thats what I meant by dehumidifying etc.. What I meant was it doesn't warm the car up - thats the heaters so don't concentrate on the AC not allowing the car to warm up. There's something with the heating system if its taking too long. Does the car temp move to middle ok or does it take a long time too? As DJ Syxx said - you should use it as often as possible to keep the system working proper. Link to comment Share on other sites More sharing options...
thejames Posted March 1, 2011 Author Report Share Posted March 1, 2011 Well, just had it re-gassed... What a difference! It's like a fridge/oven at the flick of a switch! Driving home I was toasty on a low-blowing 23 degrees. I been running around on 32 degrees since November! Also threw some water in the rad which may well have made a difference. Happy chappy. Well impressed with the garage too. Gerry @ GS Auto's on the Godstone Road in Whyteleafe. Top bloke. Morale of the story: If your A/C isn't quite hitting the spot, consider a re-gas. Link to comment Share on other sites More sharing options...
zimzimmer46 Posted March 1, 2011 Report Share Posted March 1, 2011 Good job m8. Gonna do mine myself soon. Link to comment Share on other sites More sharing options...
Devil2575 Posted March 2, 2011 Report Share Posted March 2, 2011 Please explain how the aircon can heat the car up as well as cool it? The Air conditioning stuff i.e. the condenser and the compressor is simply a refrigeration circuit that allows the cooling of the air. The climate control unit then uses this cool air along with warm air from the engine to achieve the desired temperature set point. If you set it to hot it takes the air warmed by the engine, if you set it to cold it takes the air cooled by the aircon circuit. In between and it uses a combination of the two. On cars without aircon the cold air is simply from outside and even on cars with aircon if the outside air temperature is low enough it will use this air in preference to runing the aircon compressor. Aircon units do generate heat but i'm struggling to understand how this could be used to warm the car faster. As the compressor compresses the refrigerant it heats up, this then runs through the condenser where it is cooled by air drawn through either by the motion of the car and/or the aircon fan. Quite how this heat could be used to warm the car is beyond me, especially since the condenser only sees the warm compressed fluid when the aircon is running i/e. the climate control unit requires cold air to reach the desired temperature set point. Putting your aircon on a cold day doesn't actually run the aircon system unless the interior of the car is appreciably hotter than the outside temperaturei.e. the climate contro which when you just get in, it isn't, or you set your front vents to cold. Even then the aircon system won't run at all if the ambient temperature is below a certain point anyway. In short, the length of time the heaters take to start blowing hot is dictated by the engine warming up and not whether you have the aircon switched on or not, unless i'm very much mistaken. Link to comment Share on other sites More sharing options...
Devil2575 Posted March 2, 2011 Report Share Posted March 2, 2011 Also threw some water in the rad which may well have made a difference. Which I suspect has more to do with your system now blowing hot air. The cars heater is connected to the radiator circuit and if your coolant level is low one of the first signs is that your heater doesn't work properly. Like when the radiators in your house need bleeding because they have air in them. Link to comment Share on other sites More sharing options...
Devil2575 Posted March 2, 2011 Report Share Posted March 2, 2011 You should be able to use AC to warm the car up as well. If yours is taking a long time to warm up then you probably need to have it looked at. AC should warm the car up faster than relying on the engine. The only way the AC could be used to warm the car up faster is if the system could be run in such a way that the evaporator became the condensor and vice versa, or the warm air from the condensor could be chaneled into the cabin while the cold air from the evaporator was discarded Link to comment Share on other sites More sharing options...
mit Posted March 2, 2011 Report Share Posted March 2, 2011 (edited) The only way the AC could be used to warm the car up faster is if the system could be run in such a way that the evaporator became the condensor and vice versa, or the warm air from the condensor could be chaneled into the cabin while the cold air from the evaporator was discarded Yeah, it's called reverse cycle and it's the main difference between a car that has climate control and one that has simple air conditioning. The air conditioning in my flat is also reverse cycle. It's quite handy when my boiler decides it doesn't want to boil anymore. It's been around since 1954. Edit - I just read your long description but it's not quite right. That's how the air mixture works on a car that has regular air conditioning and heating, not one that has climate control. Edited March 2, 2011 by mit Link to comment Share on other sites More sharing options...
Devil2575 Posted March 2, 2011 Report Share Posted March 2, 2011 Yeah, it's called reverse cycle and it's the main difference between a car that has climate control and one that has simple air conditioning. The air conditioning in my flat is also reverse cycle. It's quite handy when my boiler decides it doesn't want to boil anymore. Yes, the ability to switch between a referigeration cycle and a heat pump. I wasn't aware that the BMW system had this capability. Climate control doesn't require the car to aircon that can run as a heat pump, it can just be digital temperature control linked to valves controlling airflow and the ability to turn the compressor pump on and off. Link to comment Share on other sites More sharing options...
mit Posted March 2, 2011 Report Share Posted March 2, 2011 Yes, the ability to switch between a referigeration cycle and a heat pump. I wasn't aware that the BMW system had this capability. Climate control doesn't require the car to aircon that can run as a heat pump, it can just be digital temperature control linked to valves controlling airflow and the ability to turn the compressor pump on and off. I thought it was commonly known that climate control meant the a/c had a heat pump as well. In fact I've never known of a climate control system in a car *not* to have this capability (I wasn't born as far back as 1954)! I guess it's not as commonly known as I thought! Link to comment Share on other sites More sharing options...
Devil2575 Posted March 2, 2011 Report Share Posted March 2, 2011 I not sure it does. It might do on some cars built at a time when fuel was cheap an no one cared about mpg, but in this day and age? The advantage of a heat pump is that it will give you hot air almost imediately, a bit like aircon that blows cold in seconds (assuming your system is in good health) a heat pump will get hot quickly. So cold morning almost instant warm air. Trouble is, my BMW doesn't do this. Also the E46 has a heater matrix fitted to all models, not just those without climate fitted. Now I suppose the a/c system could be very clever and work as a heat pump until the coolant is warm enough to do the duty instead but this would be a lot of extra bits just to allow the car to blow hot air when cold. The down side of a heat pump, in a car is that you need the compressor running to heat the car. Your conventional heating system uses heat from the coolant, which would otherwise be lost to the air through the radiator, to heat the interior. A perfect example of heat integration, using energy that would normally be lost to do another duty. However your compressor uses the engines power to make heat so uses fuel. So a car with a heat pump would need to run the compressor constantly unless the interior temp you require was very close to the ambient air temperature. This is not an efficient way to heat a car when you have a free source of heat in the coolant that are are trying to get rid off anyway. Like I said, in a country where fuel price is not an issue, maybe... Link to comment Share on other sites More sharing options...
Frobius Posted March 2, 2011 Report Share Posted March 2, 2011 Hang on. Afaik, the ac won't be on if you're trying to heat. You can hear the ac clutch kicking in and out on some cars. If you select a temp warmer than current internal, it should pass air across the heater element into the cabIn. If you want colder, the system kicks in the ac compressor, cooling the bit of the system that the air passes through before getting to the cabIn. (this makes sense in my head but it's prob come out wrong) I'd be really surprised if it had a reverse cycle ac system instead of boggo heater element / exchanger. As for the rest of the system, BMW told me that the ac (cooler/dryer) doesn't come on 3 deg C or lower ambient. As for the OPs query. This can be normal, especially if you're setting 32 deg from the off! You're basically taking the slightest bit of warmth out of the heater element before it has a chance to heat up. Try turning the fan off until your engine heats up to the first line, then setting 20 or so. You'll be surprised how much quicker this is. One thing I don't like is the car seems to like to blow all the air at my feet when on auto instead of all the vents evenly. I end up just selecting screen, face and feet at the same time manually. Link to comment Share on other sites More sharing options...
mit Posted March 3, 2011 Report Share Posted March 3, 2011 (edited) Hang on. OK. So I guess thejames shouldn't have bothered to get his re-gassed then as it wouldn't have made a difference. Except it did make a difference. It's all about fuel efficiency and things now, but it wasn't in the mid 90's when the E46 was designed. Back then it was about making engines bigger and faster and little thought was given to fuel economy. The method you suggested is already available automatically as an OBC option, as I mentioned before. You just have to have it enabled by a dealer or specialist. There are also options for hot climate or cold climate where the reading on the display will be up to 4 degrees cooler or 4 degrees warmer than the actual temperature depending on what option is set on the OBC. Also you'll notice the A/C engaging and disengaging all the time on the cooling cycle because it operates by cooling as efficiently as it can rather than on some variable basis with the pump operating at different speeds, stopping then starting again the same way an electric hob might in your kitchen. My A/C at home does the same. It'll be on constantly until the whole place gets down to the temperature on the thermostat, and then it'll turn itself on and off to maintain that temperature (so strictly speaking it fluctuates around the temperature set on the thermostat). This behaviour you describe on some cars is generally on cars that have regular A/C and not automatic climate control. There's a reason why this option costs so much more; it's not just so you get a funky digital display! Edited March 3, 2011 by mit Link to comment Share on other sites More sharing options...
MisterAdam Posted March 3, 2011 Report Share Posted March 3, 2011 Is it just me that doesn't use the AC to heat up the car? I find the climate control does a good enough job of heating the car up pretty quickly. If the car's frosty I find a couple mins of front and rear demister's tends to de-ice them and then I just leave the climate control set to auto and 19 degree's celcius which warm's car up fine, that's with the heated seats on full welly aswell like Link to comment Share on other sites More sharing options...
mit Posted March 3, 2011 Report Share Posted March 3, 2011 Is it just me that doesn't use the AC to heat up the car? I find the climate control does a good enough job of heating the car up pretty quickly. If the car's frosty I find a couple mins of front and rear demister's tends to de-ice them and then I just leave the climate control set to auto and 19 degree's celcius which warm's car up fine, that's with the heated seats on full welly aswell like No you're not the only one. I don't use it either, and think it's a waste of fuel and petrol. My car heats up to normal operating temperature in about 5 minutes of driving anyway, after which it blows warm air just fine I don't have heated seats either! Link to comment Share on other sites More sharing options...
MisterAdam Posted March 3, 2011 Report Share Posted March 3, 2011 No you're not the only one. I don't use it either, and think it's a waste of fuel and petrol. My car heats up to normal operating temperature in about 5 minutes of driving anyway, after which it blows warm air just fine I don't have heated seats either! I find it also heat's up a bit quicker if you have the air recirculating until it's started to warm up a little Link to comment Share on other sites More sharing options...
mit Posted March 3, 2011 Report Share Posted March 3, 2011 I find it also heat's up a bit quicker if you have the air recirculating until it's started to warm up a little I have the recirculation set to automatic so the car does that for me Link to comment Share on other sites More sharing options...
Devil2575 Posted March 3, 2011 Report Share Posted March 3, 2011 OK. So I guess thejames shouldn't have bothered to get his re-gassed then as it wouldn't have made a difference. Except it did make a difference. You might also have noticed that he got his coolant level topped up at the same time. I'd put money on that being the reason the heater wasn't working, not the refrigerant level in the A/C circuit. The method you suggested is already available automatically as an OBC option, as I mentioned before. You just have to have it enabled by a dealer or specialist. There are also options for hot climate or cold climate where the reading on the display will be up to 4 degrees cooler or 4 degrees warmer than the actual temperature depending on what option is set on the OBC. Also you'll notice the A/C engaging and disengaging all the time on the cooling cycle because it operates by cooling as efficiently as it can rather than on some variable basis with the pump operating at different speeds, stopping then starting again the same way an electric hob might in your kitchen. My A/C at home does the same. It'll be on constantly until the whole place gets down to the temperature on the thermostat, and then it'll turn itself on and off to maintain that temperature (so strictly speaking it fluctuates around the temperature set on the thermostat). This behaviour you describe on some cars is generally on cars that have regular A/C and not automatic climate control. There's a reason why this option costs so much more; it's not just so you get a funky digital display! I'm not denying that the climate control on the E46 is not simply a digital display stuck onto basic A/C, It's a fully automated temperature control system. What I am saying is that I don't believe that it can operate in reverse cycle. As I said, if it could then you would be able to get heat out of it after about 30 seconds on a cold morning. I tried mine this morning and it didn't. Also I have been able to find no reference to the BMW system having a heat pump. However in the haynes manual it describes the climate control system as using a conventional heater matrix for heat and an a/c circuit for cold. Link to comment Share on other sites More sharing options...
Devil2575 Posted March 3, 2011 Report Share Posted March 3, 2011 Is it just me that doesn't use the AC to heat up the car? I find the climate control does a good enough job of heating the car up pretty quickly. All year round I leave my temp set to 21 degC and the A/C button on. I then just let the climate control do it's thing. Link to comment Share on other sites More sharing options...
