Front Manual Air Conditioning System: Description

WARNING: This page is about a different car, the 2018 Nissan NV3500 HD, 2018 Nissan NV2500 HD, and 2018 Nissan NV1500. However, it is still accessible from the selected car via links, so may be relevant.

The front air control provides voltage to the gate of the power transistor based on the position of the blower control dial. By applying a variable voltage to the gate, the power transistor controls the current flow to ground, thereby controlling the speed of the blower motor. The front air control monitors the blower motor voltage and the blower motor ground circuits. The blower control dial has 26 detents, each detent outputting a different gate voltage to the power transistor, allowing for 26 different fan speeds.

In addition to manual control of the air flow, the front air control will modify the customer selection during certain conditions. During heater warm-up, the front air control will move the intake door from fresh to partial recirculation. The front air control will illuminate the fresh indicator. Also, if the intake temperature is too hot, the intake door will move to partial or full recirculation. The front air control will illuminate the fresh indicator.

When the blower control dial is turned off, the front air control will remember the customer selected intake air position (REC or FRE), the current mode, and the A/C state. Upon turning to any blower speed, the front air control will return to the previous mode and state, and if the previous state was MAX A/C, the front air control will illuminate the REC LED.

Blower control dial detents	MAX A/C, VENT, and B/L	FOOT, D/F0	D/F1, DEF	P/REC Mode
OFF	0.00 volts	0.00 volts	0.00 volts	0.00 volts
1	3.25 volts	3.75 volts	3.75 volts	3.75 volts
2	3.50 volts	4.00 volts	4.00 volts	4.00 volts
3	3.75 volts	4.25 volts	4.25 volts	4.25 volts
4	4.00 volts	4.50 volts	4.50 volts	4.50 volts
5	4.50 volts	4.75 volts	4.75 volts	4.75 volts
6	4.75 volts	5.00 volts	5.00 volts	5.00 volts
7	5.00 volts	5.50 volts	5.50 volts	5.50 volts
8	5.25 volts	5.75 volts	5.75 volts	5.75 volts
9	5.50 volts	6.00 volts	6.00 volts	6.00 volts
10	5.75 volts	6.25 volts	6.25 volts	6.25 volts
11	6.25 volts	6.50 volts	6.50 volts	6.50 volts
12	6.50 volts	6.75 volts	6.75 volts	6.75 volts
13	6.75 volts	7.00 volts	7.00 volts	7.00 volts
14	7.00 volts	7.25 volts	7.25 volts	7.25 volts
15	7.50 volts	7.50 volts	7.50 volts	7.50 volts
16	7.75 volts	7.75 volts	7.75 volts	7.75 volts
17	8.00 volts	8.00 volts	8.25 volts	8.00 volts
18	8.25 volts	8.25 volts	8.50 volts	8.25 volts
19	8.50 volts	8.50 volts	8.75 volts	8.50 volts
20	8.75 volts	8.75 volts	9.00 volts	8.75 volts
21	9.00 volts	9.00 volts	9.25 volts	9.00 volts
22	9.25 volts	9.25 volts	9.50 volts	9.25 volts
23	9.75 volts	9.75 volts	10.00 volts	9.50 volts
24	10.25 volts	10.25 volts	10.25 volts	10.75 volts
25	10.50 volts	10.50 volts	10.50 volts	10.00 volts
26	10.75 volts	10.75 volts	12.00 volts	10.25 volts
12 = Max blower voltage

In order for the IPDM E/R to complete a compressor ON request, the following conditions must be met:

The BCM detects a Fan ON signal from the front air control. The front air control grounds the fan ON signal monitored by the BCM when the blower speed dial is in any of the fan speed positions.
The BCM detects an A/C ON signal from the front air control. The front air control grounds the A/C ON signal monitored by the BCM when:
- The A/C switch is pressed. The A/C switch LED illuminates and the front air control grounds the A/C ON signal monitored by the BCM. Any mode control button except D/F may be selected.
- The A/C switch is OFF, and the MAX A/C button is pressed. The A/C switch LED will automatically illuminate and the front air control grounds the A/C ON signal monitored by the BCM.
- The A/C switch is OFF, and the mode button for either D/F or DEF is selected. The front air control grounds the A/C ON signal monitored by the BCM, but it does not illuminate the A/C switch LED
The intake temperature value must be within the specified range.

NOTE: If the compressor was engaged by pressing the D/F or DEF mode buttons, and the time spent in either mode exceeds 1 minute, then the compressor stays requested, even when modes other than D/F or DEF are selected, until either:

The ignition switch is turned OFF.
The blower speed dial is turned completely counterclockwise to the OFF position.
The A/C switch is manually turned OFF.

In other words, the compressor ON request cannot be turned off in D/F or DEF modes.