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post #1 of 37 (permalink) Old 06-13-2009, 09:40 AM Thread Starter
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Exclamation A/C will not come on. Need Help/Advise

Hello Everyone,

I have a 2005 Elise which is having a problem and with it 95 degrees here I need some help/advise.

Just got back from Car's and Coffee, Jacksonville Fl. , tried to use my A/C for the first time this year (was working fine last summer) and it will not come on, here is what I have done/checked so far. I do have a dealer in Jacksonville but trying to see if there is anything I can do myself before going that route.

On the switch panel:

Fan switch works normal in all speeds.
Temp switch works normal when going from hot to cold.
Position switch works normal when going from floor to vents to defrost etc...

A/C button does nothing and the blue light does not come on.
Recir button does nothing and the blue light does not come on.

Car runs fine, idle does not change when A/C button depressed and I do not hear the compressor engage or anything else happen for that matter.

Car lives in a dehumidifed garage under cover, car has about 9K miles.

What I have checked done:

Main fuse box under passenger side front panel,

Fuse 19 (a/c compresor relay) a twenty amp fuse is good and HAS power, engine running / ac fan running.

Engine fuse box next to ecu,

Fuse R8 (recir pump) a five amp fuse is good but has no power, engine running / ac fan running.

Passenger foot well fuse box,

Fuse C4 (ac compressor) a seven one/half amp fuse is good but has no power, engine running / ac fan running.

Switch panel, removed

When I checked all wires connected solid, removed connection to A/C switch and probed all three wires with a grounded test light, no power at any of them, engine running / ac fan running.

Thats it so far, I am at a loss at this point, I did have the a/c system drained and recharged last summer and it ran fine (as fine as a Elise can) and I have done all the listed A/C mods for improvement.

Any help would be apprecieated , if the system leaked down some is there a low pressure switch someplace that interupts power to everything ?

I dont believe this is what happend it seems to be an electrical fault of some kind.

All other electrics work fine,

Todd in Georgia

Last edited by Torro; 06-13-2009 at 10:22 AM. Reason: correction
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post #2 of 37 (permalink) Old 06-13-2009, 09:54 AM
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Todd,
I find it hard to understand that there is no power on the incoming side of Fuse F19, this fuse is a direct supply off of the battery, via a front + stud & splice "L" at the fusebox. As the other, front fed circuits are OK, it can't be the stud. All that is left is the splice "L" and the incoming connection at fuse F19. Check both sides of that fuse again and remember to ground the meter and let us know your findings.
Michael
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Originally Posted by Torro View Post
Hello Everyone,
I have a 2005 Elise which is having a problem and with it 95 degrees here I need some help/advise.
Just got back from Car's and Coffee, Jacksonville Fl. , tried to use my A/C for the first time this year (was working fine last summer) and it will not come on, here is what I have done/checked so far. I do have a dealer in Jacksonville but trying to see if there is anything I can do myself before going that route.
On the switch panel:
Fan switch works normal in all speeds.
Temp switch works normal when going from hot to cold.
Position switch works normal when going from floor to vents to defrost etc...
A/C button does nothing and the blue light does not come on.
Recir button does nothing and the blue light does not come on.

Car runs fine, idle does not change when A/C button depressed and I do not hear the compressor engage or anything else happen for that matter.

Car lives in a dehumidifed garage under cover, car has about 9K miles.

What I have checked done:

Main fuse box under passenger side front panel,

Fuse 19 (a/c compresor relay) a twenty amp fuse is good but has no power, engine running / ac fan running.

Engine fuse box next to ecu,

Fuse R8 (recir pump) a five amp fuse is good but has no power, engine running / ac fan running.

Passenger foot well fuse box,

Fuse C4 (ac compressor) a seven one/half amp fuse is good but has no power, engine running / ac fan running.

Switch panel, removed

When I checked all wires connected solid, removed connection to A/C switch and probed all three wires with a grounded test light, no power at any of them, engine running / ac fan running.

Thats it so far, I am at a loss at this point, I did have the a/c system drained and recharged last summer and it ran fine (as fine as a Elise can) and I have done all the listed A/C mods for improvement.

Any help would be apprecieated , if the system leaked down some is there a low pressure switch someplace that interupts power to everything ?

I dont believe this is what happend it seems to be an electrical fault of some kind.

All other electrics work fine,

Todd in Georgia

Last edited by SirLotus; 06-13-2009 at 10:24 AM.
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post #3 of 37 (permalink) Old 06-13-2009, 10:21 AM Thread Starter
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Viper,

You are correct, I just checked it again it is "hot" on both sides, engine running, fan switch running. I was doing too much and not taking notes.

Also under the dash passenger side there are two little fuse boxes together, Fusebox C is the only one shown in my owners manual and has fuses C1-C4, C1-3 are all "hot" the C4 one for the AC Compressor has no power, engine running and fan switch running, what is the other fuse box it has only one 15 amp fuse which is "hot" but it is not shown in the manual ?

Todd
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post #4 of 37 (permalink) Old 06-13-2009, 10:40 AM
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C5 is for the driving lights. Ok if what you have described to me is accurate then the answer is the Compressor Relay is probably faulty in the AC control module. Outside possibility is the Trinary Switch or thermostat which will not allow the system to work with either low or high pressures, have your refrigerant checked
Michael
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Viper,

You are correct, I just checked it again it is "hot" on both sides, engine running, fan switch running. I was doing too much and not taking notes.

Also under the dash passenger side there are two little fuse boxes together, Fusebox C is the only one shown in my owners manual and has fuses C1-C4, C1-3 are all "hot" the C4 one for the AC Compressor has no power, engine running and fan switch running, what is the other fuse box it has only one 15 amp fuse which is "hot" but it is not shown in the manual ?

Todd

Last edited by SirLotus; 06-13-2009 at 10:56 AM.
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post #5 of 37 (permalink) Old 06-13-2009, 10:55 AM Thread Starter
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Viper

Is this the part you mean "The A.C. relay module A117M0038F has a brown label marked YWB100800"it is located right next to the main fuse box in the passenger side service compartment.

If this is the part they say it has been replaced by B117M0038 and call it a 06 Fan Control Module for $178.00 plus tax/shipping.

Here is the link:

Lotus Garage[cid]=0&s[short_desc]=Y&s[title]=Y&s[full_desc]=Y&s[search]=A117M0038F

Todd

PS is there any way to check before buying this part ?
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post #6 of 37 (permalink) Old 06-13-2009, 11:20 AM
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That's the one. Testing may be difficult because just jumpering the relay contacts may get the system to work but it could still be the that the relay coil is either defective or not being controlled by the ECU/Trinary switch.
You could check the resistance of the relay coil across the pins that the Green and Blue/Black wire terminate, resistance should be in excess of 3 ohms. Before buying the module I would have the refrigerant checked.
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Viper

Is this the part you mean "The A.C. relay module A117M0038F has a brown label marked YWB100800"it is located right next to the main fuse box in the passenger side service compartment.

If this is the part they say it has been replaced by B117M0038 and call it a 06 Fan Control Module for $178.00 plus tax/shipping.

Here is the link:

Lotus Garage[cid]=0&s[short_desc]=Y&s[title]=Y&s[full_desc]=Y&s[search]=A117M0038F

Todd

PS is there any way to check before buying this part ?

Last edited by SirLotus; 06-13-2009 at 11:33 AM.
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post #7 of 37 (permalink) Old 06-13-2009, 11:24 AM Thread Starter
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Viper

Firstly thanks for all the help, I will check the R134 level, the book says it should be 1.2 pounds do you by chance know what the pressures should be on the gauges ?

Thanks

Todd
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post #8 of 37 (permalink) Old 06-13-2009, 11:34 AM
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Besides fuse, not much else that can cause this but a line leak. It does happen. You need to kick the AC once a month just to keep the seals lubricated.
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post #9 of 37 (permalink) Old 06-13-2009, 11:36 AM
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Todd,
Your welcome. I modified my above post, please check.
I really don't know about the gauge.
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Viper

Firstly thanks for all the help, I will check the R134 level, the book says it should be 1.2 pounds do you by chance know what the pressures should be on the gauges ?

Thanks

Todd
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post #10 of 37 (permalink) Old 06-14-2009, 04:40 AM
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134a charge

Torro,

You can't really check the refrigerant total charge amount with pressure gauges - especially not when the system isn't running. However, you may not need to do that. There is a safety switch on the system to prevent the compressor from running when there is too little refrigerant in the system. The vapor pressure of 134a at room temperature (about 70 ºF) is around 73 psig. That's what the pressure should be on any static (non-running) 134a system. That pressure is independent of the total charge as long as there is some liquid refrigerant in the system - which there must be to operate properly. If the static system pressure is below about 70 psig (the exact number will be temperature dependent) then you've lost so much refrigerant that there is no longer liquid in the system. The system can be recharged by weight and/or by monitoring the low-side pressure. The low side pressure must at least be above atmospheric pressure to prevent water infiltration into the system. The low-side pressure (with the system running) should be high enough that the evaporator does not ice (usually about 25-30 psig). There's a chart of vapor pressure vs temperature for several common refrigerants here.

Unless you have a refrigerant recovery system you shouldn't really fool with the charge. Although 134a is not chlorine containing (it doesn't cause ozone depletion) it does have a high global warming index (it's a strong ir absorber). If your system has leaked out, you'll need to find the leak and fix it rather than continuing to release 134a into the atmosphere by just recharging it.

A.J.

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Last edited by Valenz; 06-14-2009 at 09:27 AM.
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post #11 of 37 (permalink) Old 06-14-2009, 05:03 AM Thread Starter
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Hi Val

I cant imagine that the system has completely leaked out, but I guess I could be wrong it sure seems like an electrical failure to me, like the relay. I am going to put gauges on it in a few minutes and report back on my readings here.

Todd
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post #12 of 37 (permalink) Old 06-14-2009, 11:16 AM Thread Starter
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Ok guy's here is what I did today,

I attached my a/c manifold gauges to the car and jumpered fuse C4 it turned on my compressor the system appeared low and the cooling temp out the vents was poor. I then proceeded to add one 12 ounce can of 134a to the system it took about 15 minutes and resulted in a reading of 44 psi on the low side and 350 psi on the high side (sounds high to me). The temp coming out of the vent stationary is 68 degrees the temp outside is 90 degrees. I then shut down the car and removed the jumper wire the result is the same as before, I have the exact same situation.

So do I bite the bullet and purchase a ac relay module (leaning toward) for $178 bucks or the trinary switch for god knows how much or just drop the car at the dealer ?

Todd,
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post #13 of 37 (permalink) Old 06-14-2009, 11:37 AM
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I am not sure of what you described, jumpering Fuse C4 and it works obviously implies a bad fuse??? Are you sure this is what you jumped and not the relay contact. BTW my vent temps at 90' ambient starts out in the low 40's and ends up at around 50'. The Trinary switch only allows the compressor to operate between 29 - 464 psi (2 - 32 bar)
Michael
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Ok guy's here is what I did today,
I attached my a/c manifold gauges to the car and jumpered fuse C4 it turned on my compressor the system appeared low and the cooling temp out the vents was poor. I then proceeded to add one 12 ounce can of 134a to the system it took about 15 minutes and resulted in a reading of 44 psi on the low side and 350 psi on the high side (sounds high to me). The temp coming out of the vent stationary is 68 degrees the temp outside is 90 degrees. I then shut down the car and removed the jumper wire the result is the same as before, I have the exact same situation.

So do I bite the bullet and purchase a ac relay module (leaning toward) for $178 bucks or the trinary switch for god knows how much or just drop the car at the dealer ?

Todd,

Last edited by SirLotus; 06-14-2009 at 12:09 PM.
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post #14 of 37 (permalink) Old 06-14-2009, 01:11 PM Thread Starter
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Sorry for the fusiion, what I meant by jumping C4 is, I removed the fuse from it's holder (the fuse is good) then as there is no power to the hot side of the fuse from the relay I jumpered to the compressor side of the fuse from another 12 volt source which bypassed the relay and turned on the compressor.

Problem is I dont know what is causing the relay not to close, it could be the relay itself or the trinary switch or some other gremlin I guess...

I am going to take the thing to Jacksonville to the dealer on Mon or Tue, it just kills me to do it due to the cost and down time, but in the long run that is probably the best thing to do I guess.

I have done both the A/C mods, open footwell plates and covered the intake openings behind the grill and the best I can get is 65 degrees so it sounds like I may have had a problem all along and it just finally gave up.

Todd
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post #15 of 37 (permalink) Old 06-14-2009, 01:11 PM Thread Starter
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Oh forgot my emoticon

Todd
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post #16 of 37 (permalink) Old 06-14-2009, 01:22 PM
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My guess is that the Trinary switch is shutting off the system due to low or high pressure. Bypassing the Trinary may be tricky and possible dangerous to the compressor.
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Sorry for the fusiion, what I meant by jumping C4 is, I removed the fuse from it's holder (the fuse is good) then as there is no power to the hot side of the fuse from the relay I jumpered to the compressor side of the fuse from another 12 volt source which bypassed the relay and turned on the compressor.

Problem is I dont know what is causing the relay not to close, it could be the relay itself or the trinary switch or some other gremlin I guess...

I am going to take the thing to Jacksonville to the dealer on Mon or Tue, it just kills me to do it due to the cost and down time, but in the long run that is probably the best thing to do I guess.

I have done both the A/C mods, open footwell plates and covered the intake openings behind the grill and the best I can get is 65 degrees so it sounds like I may have had a problem all along and it just finally gave up.

Todd
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post #17 of 37 (permalink) Old 06-14-2009, 01:38 PM Thread Starter
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Mike

My pressures are within the ranges covered for operation by the trinary switch 44 psi on the low side and 360 ish on the high side, the switch alows pressures between 29 and 464, so I am ok there unless the switch has failed, my guess is either a failed switch or failed relay/module for the A/C, I believe this module is located behind the front passenger side wheel liner on a shelf of sometype.

Todd
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post #18 of 37 (permalink) Old 06-14-2009, 01:39 PM Thread Starter
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When I get the car back from the dealer I think I will do your insulation trick on the firewall in the front and the side sill's as well. I did you mod's on opening the foot wells and covering the intakes in the front.

Todd
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post #19 of 37 (permalink) Old 06-14-2009, 02:06 PM
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Todd,
You are right it does appear to be in range. The Module is located next to the fuse box up front, easy to get to. I have a spare one that I keep for moments like this, wish you were close by You don't have another owner nearby who would let you try theirs do you?
You could try to bypass the Trinary,which would tell you a lot, but frankly I am not sure of the consequences.
When insulating the sills check with me and I will give you the tricks and pitfalls I have a patten.
Michael
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Mike
My pressures are within the ranges covered for operation by the trinary switch 44 psi on the low side and 360 ish on the high side, the switch alows pressures between 29 and 464, so I am ok there unless the switch has failed, my guess is either a failed switch or failed relay/module for the A/C, I believe this module is located behind the front passenger side wheel liner on a shelf of sometype.

When I get the car back from the dealer I think I will do your insulation trick on the firewall in the front and the side sill's as well. I did you mod's on opening the foot wells and covering the intakes in the front.
Todd
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post #20 of 37 (permalink) Old 06-14-2009, 02:17 PM Thread Starter
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Mike

I live just across the state line from Jacksonville FL on I-95, I looked for the module next to the main fuse box under the passenger side service panel and did not see it ? I thought it was attached to the passenger side front wheel liner sitting on a little shelf ?

I am afraid to do more bypassing to tell the truth, I was nervous about jumping that 7.5 amp C4 fuse but I needed the compressor to run to see the pressures. No other owners close by, nearest is in Jax and I would not want to ask him to take a part off his car just to try on mine, now on the other hand if you want to drop your spare in the mail to me I would not mind it

Todd
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