Jersey Jim
Member
Am new to the forum, this is my 1st post. 2 years ago I bought this Expy from a friend at work, strictly for towing my boat. Been very happy with it except a few nuisances. One I finally got around to addressing is the A/C blowing cold air intermittently. Usually works only when the engine first starts and is cold. Usually stops working 10 minutes into a trip, but once in a while I get lucky and can make the hour trip to my boat slip.
Well I finally got fed up and dug into it. The seller tells me his mechanic claims it is a blend door, because once the air stops blowing cold, it comes out of the vents 10 degrees warmer than the ambient outside. I did not agree with this, as the blend door seems to be disabled on "max A/C", Understandably. He also said he put in a new compressor and clutch-coil. What year I do not know. I purchased it in August of 2016.
So this week I dug in and focused on the A/C clutch, and sure enough, it stops cycling when the problem occurs. I ruled out (jumped out) the high pressure switch and low pressure switch. Still no cycling when this problem decides to occur. The only other (3rd thing) that seems to cycle/inhibit the clutch, is the evaporator air-inlet temperature. This didn't seem to be documented on the diagrams (4 pages from dealer), but I observed 100% duty-cycle of the clutch when cabin (evaporator air return) is 61F and warmer. Below 61F inside and I observed the clutch beginning to cycle off a few percent. Down as cold as 58F in the cabin, on floor out of direct airflow, the clutch repeatably cycles 6 seconds off, about 70% "on" is about as much as the cycling will allow at this cold temperature. The closer to 61F, the "off-time" remains 6 seconds, but the "on-time" extends to as long as about 3 minutes. Above 61F inside, and the compressor stays on 100%, at idle, inside my barn at 75F ambient. This seems to be some PID algorithm, with a proportional band beginning below 61F.
Long story short (too late), the problem was the clutch-coil resistance changing from the normal 3-5 ohms when it works, to 6,000 ohms and as high as 100,000 ohms when it acted up. I located the small auxiliary relay box near the driver side headlight, under intake ducts, and removed the clutch relay. I could feel it clicking as I plugged it in, indicating it was being commanded to activate clutch. I figured the arcing just ate up the silver on the contacts... no such luck. I removed relay and looked for 4 ohms on relay socket pin to ground. 6k ohms and higher, depending on temperature of engine. This relay has 12 VDC positive at relay at all times, even without key. I removed relay cap and plugged it back in. After engine cooled down I squeezed the relay armature with fingers, and heard the clutch clicking as I should. I dropped the skid-plate underneath, as the compressor is mounted very low. I pulled coil connector apart (2-inches from clutch), and found oxidized connector pins. After scraping and spraying pins clean, I packed both connectors with dielectric grease, then re-connected them. I figure being this connector is about the lowest part of the engine, it was picking up water, snow, salt, etc. I even packed the wire entry points with the grease. It has been working flawlessly for MANY hours over past few days!!
It makes me wonder how many clutch coils get changed without ruling out this vulnerable link? Between a replaced coil having new connector pins, and the mere scraping of the female harness side of the connector by removing old and replacing new, these 2 "scrapings" of the female pins is most often enough to get it working for a year or two before the oxidation grows/returns. I think this explains why my friend had the compressor and clutch replaced but it started failing again. Please check and clean this connection before throwing in the towel (money) on replacement.
Now on to my question.... the rear evaporator seems to be dripping condensate nicely from the rear area onto the ground, but I never see a single drop on the ground from the front evaporator. Can anyone tell me where a tube should be exiting, so that I may rod it out to unplug/clean it??
Thanks in advance.
PS... And at what PSI does the low-pressure freon cycling switch interrupt at, as well as high-pressure cut-out switch? (R134A)
Well I finally got fed up and dug into it. The seller tells me his mechanic claims it is a blend door, because once the air stops blowing cold, it comes out of the vents 10 degrees warmer than the ambient outside. I did not agree with this, as the blend door seems to be disabled on "max A/C", Understandably. He also said he put in a new compressor and clutch-coil. What year I do not know. I purchased it in August of 2016.
So this week I dug in and focused on the A/C clutch, and sure enough, it stops cycling when the problem occurs. I ruled out (jumped out) the high pressure switch and low pressure switch. Still no cycling when this problem decides to occur. The only other (3rd thing) that seems to cycle/inhibit the clutch, is the evaporator air-inlet temperature. This didn't seem to be documented on the diagrams (4 pages from dealer), but I observed 100% duty-cycle of the clutch when cabin (evaporator air return) is 61F and warmer. Below 61F inside and I observed the clutch beginning to cycle off a few percent. Down as cold as 58F in the cabin, on floor out of direct airflow, the clutch repeatably cycles 6 seconds off, about 70% "on" is about as much as the cycling will allow at this cold temperature. The closer to 61F, the "off-time" remains 6 seconds, but the "on-time" extends to as long as about 3 minutes. Above 61F inside, and the compressor stays on 100%, at idle, inside my barn at 75F ambient. This seems to be some PID algorithm, with a proportional band beginning below 61F.
Long story short (too late), the problem was the clutch-coil resistance changing from the normal 3-5 ohms when it works, to 6,000 ohms and as high as 100,000 ohms when it acted up. I located the small auxiliary relay box near the driver side headlight, under intake ducts, and removed the clutch relay. I could feel it clicking as I plugged it in, indicating it was being commanded to activate clutch. I figured the arcing just ate up the silver on the contacts... no such luck. I removed relay and looked for 4 ohms on relay socket pin to ground. 6k ohms and higher, depending on temperature of engine. This relay has 12 VDC positive at relay at all times, even without key. I removed relay cap and plugged it back in. After engine cooled down I squeezed the relay armature with fingers, and heard the clutch clicking as I should. I dropped the skid-plate underneath, as the compressor is mounted very low. I pulled coil connector apart (2-inches from clutch), and found oxidized connector pins. After scraping and spraying pins clean, I packed both connectors with dielectric grease, then re-connected them. I figure being this connector is about the lowest part of the engine, it was picking up water, snow, salt, etc. I even packed the wire entry points with the grease. It has been working flawlessly for MANY hours over past few days!!
It makes me wonder how many clutch coils get changed without ruling out this vulnerable link? Between a replaced coil having new connector pins, and the mere scraping of the female harness side of the connector by removing old and replacing new, these 2 "scrapings" of the female pins is most often enough to get it working for a year or two before the oxidation grows/returns. I think this explains why my friend had the compressor and clutch replaced but it started failing again. Please check and clean this connection before throwing in the towel (money) on replacement.
Now on to my question.... the rear evaporator seems to be dripping condensate nicely from the rear area onto the ground, but I never see a single drop on the ground from the front evaporator. Can anyone tell me where a tube should be exiting, so that I may rod it out to unplug/clean it??
Thanks in advance.
PS... And at what PSI does the low-pressure freon cycling switch interrupt at, as well as high-pressure cut-out switch? (R134A)
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