[MBZ] 1983 300D Fuse and AC Issues
Speaking of fuses... I have intermittent issues with my ac compressor/heater fan fuse. Normally it stays working (though you can see visual distortions due to heating in the fuse element and or the fuse itself if it's plastic), normally the times it actually blows seems to be if I try to do max ac with max fan. Is there anything I should look for that might solve this issue? I think I may just try to get one of those circuit breakers that are made to plug into the flat blade fuses and somehow get it to fit in where the fuse goes. That would avoid the problem of having to find a place to pull over and pop the hood and replace it. And speaking of AC... I've been monkeying with adding R134 to my system (this being my first time, though the previous owner had converted it). It does seem to be working as the compressor is now kicking on, and I got it up to around maybe 35psi. But according to the can I'd probably rather be closer to 55psi... Now, if I've got this thing figured out, I'll never be able to fully add a 13oz can as I can only empty it until the pressures are equalized. Still, I've now added *about* 3 cans (I learned on the first one that as much as it says shake well before using, they're so full that you can't really shake much, but if you don't shake it during the adding, you'll only put about 1/4-1/2 the can in). Still, it seems like it should only take about 3 cans to fill the system (the label reads 2.2lbs), yet on the 3rd can I just put in, I still couldn't seem to get the pressure much over 35psi. Am I just adding more to the system that is cycling and that's why I'm not seeing the immediate increase? Or do I more likely have a leak? Or am I missing something else obvious? Thanks! Levi 83' 300D
Re: [MBZ] 1983 300D Fuse and AC Issues
Check the aux fan for drag -- if the bearings are going out, it will draw way too much current and fry the fuse. Also check the fuse contacts -- those "torpedo" fuses are prone to corrosion, and the 25A ones also tend to burn the contact that hold it in place. If they are dirty, they overheat and cause the fuse to fail due to excessive current flow for the very limited contact area. Polish with some very fine sandpaper or 3M abrasive pad and grease with lithium grease. Peter
Re: [MBZ] 1983 300D Fuse and AC Issues
Ok, pressures are all relative, you really need to know low and high side pressures to get a full picture of what's happening. Also need to have an idea of the ambient temperature. The temperature/pressure chart at www.aircondition.com can help there. Also, it sounds like you perhaps do not have a set of manifold gauges? Mandatory for A/C work, Harbor Freight sells a set for $50 or a bit less on sale. An easy way to cheat is to monitor your center vent temperature. I like to watch the temperature as I add refrigerant, and of course quit when the temperature stops going down. You want to watch that especially with R134, because I thought that 2.2 pounds was the weight for R12. R134 should be around 25% less... Tjohn 82 300 SD 230K On 4/23/06, Levi Smith <[EMAIL PROTECTED]> wrote: > > > And speaking of AC... I've been monkeying with adding R134 to my system > (this being my first time, though the previous owner had converted > it). It > does seem to be working as the compressor is now kicking on, and I got it > up > to around maybe 35psi. But according to the can I'd probably rather be > closer to 55psi... > Now, if I've got this thing figured out, I'll never be able to fully add a > 13oz can as I can only empty it until the pressures are equalized. > Still, I've now added *about* 3 cans (I learned on the first one that as > much as it says shake well before using, they're so full that you can't > really shake much, but if you don't shake it during the adding, you'll > only > put about 1/4-1/2 the can in). > Still, it seems like it should only take about 3 cans to fill the system > (the label reads 2.2lbs), yet on the 3rd can I just put in, I still > couldn't > seem to get the pressure much over 35psi. Am I just adding more to the > system that is cycling and that's why I'm not seeing the immediate > increase? Or do I more likely have a leak? Or am I missing something > else > obvious? > > Thanks! > Levi > 83' 300D > ___ > http://www.striplin.net > For new parts see official list sponsor: http://www.buymbparts.com/ > For used parts email [EMAIL PROTECTED] > > To Unsubscribe or change delivery options go to: > http://striplin.net/mailman/listinfo/mercedes_striplin.net >
Re: [MBZ] 1983 300D Fuse and AC Issues
And speaking of AC... I've been monkeying with adding R134 to my system (this being my first time, though the previous owner had converted it). It does seem to be working as the compressor is now kicking on, and I got it up to around maybe 35psi. But according to the can I'd probably rather be closer to 55psi... Even 35 psi sounds too high for the low-side pressure. Get a set of real gauges, both high and low side in a service manifold. Now, if I've got this thing figured out, I'll never be able to fully add a 13oz can as I can only empty it until the pressures are equalized. The low side is supposed to have suction below that of the ambient temperature's vapor pressure of the refrigerant. That way the only thing left in the can is a vapor charge of that volume, a minuscule fraction of the total amount of refrigerant. Still, I've now added *about* 3 cans (I learned on the first one that as much as it says shake well before using, they're so full that you can't really shake much, but if you don't shake it during the adding, you'll only put about 1/4-1/2 the can in). Cans may be mixed refrigerants, or mixed with oil that you want to get out too. I always charge as a liquid (upside down) but at a slow rate so that it evaporates before it hits the compressor. Did I mention? Get a real set of gauges. And a FLAPS book on automotive AC servicing. You'll learn a lot! -- Jim
Re: [MBZ] 1983 300D Fuse and AC Issues
On 4/23/06, Jim Cathey <[EMAIL PROTECTED]> wrote: > > Get a real set of gauges. And a FLAPS book on > automotive AC servicing. You'll learn a lot! > Haynes makes a good one (book, not set of gauges), though it is too basic to talk much about conversion issues or refrigerants other than R12: http://www.amazon.com/gp/product/1563923815 Does the $50 Harbor Freight gauge/manifold/hoses/adapters outfit count as "real"? Alex Chamberlain, coincidentally headed to Harbor Freight tomorrow with a 10% off coupon '87 300D Turbo '93 Isuzu Trooper
Re: [MBZ] 1983 300D Fuse and AC Issues
Does the $50 Harbor Freight gauge/manifold/hoses/adapters outfit count as "real"? Yes. Anything built for the purpose as opposed to the cheap and nasty tire gauge that some cans of goo have on them. -- Jim
Re: [MBZ] 1983 300D Fuse and AC Issues
The Aux fan is the one in front of the radiator, right? That one uses a different fuse, doesn't it? The one I'm referring to seems to handle the ac compressor clutch and the cabin fan. It's only a 16A fuse. But some cleaning would probably be a good idea... (: Thanks! Levi On 4/23/06, Peter Frederick <[EMAIL PROTECTED]> wrote: > > Check the aux fan for drag -- if the bearings are going out, it will > draw way too much current and fry the fuse. > > Also check the fuse contacts -- those "torpedo" fuses are prone to > corrosion, and the 25A ones also tend to burn the contact that hold it > in place. If they are dirty, they overheat and cause the fuse to fail > due to excessive current flow for the very limited contact area. > Polish with some very fine sandpaper or 3M abrasive pad and grease with > lithium grease. > > Peter > > > ___ > http://www.striplin.net > For new parts see official list sponsor: http://www.buymbparts.com/ > For used parts email [EMAIL PROTECTED] > > To Unsubscribe or change delivery options go to: > http://striplin.net/mailman/listinfo/mercedes_striplin.net >
Re: [MBZ] 1983 300D Fuse and AC Issues
Levi Smith wrote: The Aux fan is the one in front of the radiator, right? That one uses a different fuse, doesn't it? The one I'm referring to seems to handle the ac compressor clutch and the cabin fan. It's only a 16A fuse. But some cleaning would probably be a good idea... (: Both the AUX fan and the climate control blower are high current fans. Both run at near the limit of the electrical system and both draw MORE current as they age. The revised fuse block was Mercedes' solution to the problem of the blower motor drawing excessive current when running at high speed. It's the ONLY reliable solution. All the other solutions have been tried over the last 23 years and will fail (some will fail very quickly - some will take longer). Marshall -- Marshall Booth (who doesn't respond to unsigned questions) "der Dieseling Doktor" [EMAIL PROTECTED] '87 300TD 182Kmi, '85 190D 2.0 161Kmi, '87 190D 2.5 turbo 237kmi, '84 190D 2.2 229Kmi (retired)
Re: [MBZ] 1983 300D Fuse and AC Issues
So are the aux and fan and the climate control blower on the same circuit? I.e. is the problem when they're both on(same circuit), or is the problem that either one is near the limit(on their own circuit) so both are likely to cause problems to their own circuits? How much is involved in the Mercedes solution? I.e. does that mean tearing into the dash to lay new wire to the fan motor from the fuse box and/or elsewhere? Thanks! Levi On 4/24/06, Marshall Booth <[EMAIL PROTECTED]> wrote: > > Levi Smith wrote: > > The Aux fan is the one in front of the radiator, right? That one uses a > > different fuse, doesn't it? > > The one I'm referring to seems to handle the ac compressor clutch and > the > > cabin fan. It's only a 16A fuse. But some cleaning would probably be a > > good idea... (: > > Both the AUX fan and the climate control blower are high current fans. > Both run at near the limit of the electrical system and both draw MORE > current as they age. The revised fuse block was Mercedes' solution to > the problem of the blower motor drawing excessive current when running > at high speed. It's the ONLY reliable solution. All the other solutions > have been tried over the last 23 years and will fail (some will fail > very quickly - some will take longer). > > Marshall > -- > Marshall Booth (who doesn't respond to unsigned questions) >"der Dieseling Doktor" [EMAIL PROTECTED] > '87 300TD 182Kmi, '85 190D 2.0 161Kmi, '87 190D 2.5 turbo 237kmi, '84 > 190D 2.2 229Kmi (retired) > > ___ > http://www.striplin.net > For new parts see official list sponsor: http://www.buymbparts.com/ > For used parts email [EMAIL PROTECTED] > > To Unsubscribe or change delivery options go to: > http://striplin.net/mailman/listinfo/mercedes_striplin.net >
